Elliptic curve isogeny class with LMFDB label 21840.a (Cremona label 21840bf)

• Label: 21840.a
• Number of curves: $4$
• Conductor: $21840$
• CM: no
• Rank: $1$

Rank

The elliptic curves in class 21840.a have rank \(1\).

L-function data

Bad L-factors:

Prime	L-Factor
\(2\)	\(1\)
\(3\)	\(1 + T\)
\(5\)	\(1 + T\)
\(7\)	\(1 + T\)
\(13\)	\(1 - T\)

Good L-factors:

Prime	L-Factor	Isogeny Class over \(\mathbb{F}_p\)
\(11\)	\( 1 + 6 T + 11 T^{2}\)	1.11.g
\(17\)	\( 1 + 17 T^{2}\)	1.17.a
\(19\)	\( 1 + 8 T + 19 T^{2}\)	1.19.i
\(23\)	\( 1 + 23 T^{2}\)	1.23.a
\(29\)	\( 1 + 6 T + 29 T^{2}\)	1.29.g
$\cdots$	$\cdots$	$\cdots$

See L-function page for more information

Complex multiplication

The elliptic curves in class 21840.a do not have complex multiplication.

Modular form 21840.2.a.a

Isogeny matrix

The \(i,j\) entry is the smallest degree of a cyclic isogeny between the \(i\)-th and \(j\)-th curve in the isogeny class, in the LMFDB numbering.

\(\left(\begin{array}{rrrr} 1 & 2 & 3 & 6 \\ 2 & 1 & 6 & 3 \\ 3 & 6 & 1 & 2 \\ 6 & 3 & 2 & 1 \end{array}\right)\)

Isogeny graph

The vertices are labelled with LMFDB labels.

Elliptic curves in class 21840.a

LMFDB label	Cremona label	Weierstrass coefficients	j-invariant	Discriminant	Torsion structure	Modular degree	Faltings height	Optimality
21840.a1	21840bf3	\([0, -1, 0, -823576, 287950576]\)	\(15082569606665230489/7751016000\)	\(31748161536000\)	\([2]\)	\(248832\)	\(1.9228\)
21840.a2	21840bf4	\([0, -1, 0, -819096, 291233520]\)	\(-14837772556740428569/342100087875000\)	\(-1401241959936000000\)	\([2]\)	\(497664\)	\(2.2694\)
21840.a3	21840bf1	\([0, -1, 0, -12136, 235120]\)	\(48264326765929/22299191460\)	\(91337488220160\)	\([2]\)	\(82944\)	\(1.3735\)	\(\Gamma_0(N)\)-optimal
21840.a4	21840bf2	\([0, -1, 0, 42744, 1727856]\)	\(2108526614950391/1540302022350\)	\(-6309077083545600\)	\([2]\)	\(165888\)	\(1.7200\)