[[40]] is not prime (composite): [[2]] * [[2]] * [[2]] * [[5]]

Factor pairs: [[2]] * [[20]], [[4]] * [[10]], [[5]] * [[8]]

Prime neighborhood: [[29]], [[31]], [[37]], [[40]], [[41]], [[43]], [[47]]

Prime gap: 4 (interval [[37]] to [[41]])

Primes up to 40: [[2]], [[3]], [[5]], [[7]], [[11]], [[13]], [[17]], [[19]], [[23]], [[29]], [[31]], [[37]] (12 total).

[[40]] is not a centered hexagonal number.

The closest centered hexagonal numbers are [[37]] (index # [[4]]) and [[61]] (index # [[5]]).

First 20 centered hexagonal numbers: [[1]], [[7]], [[19]], [[37]], [[61]], [[91]], [[127]], [[169]], [[217]], [[271]], [[331]], [[397]], [[469]], [[547]], [[631]], [[721]], [[817]], [[919]], [[1027]], [[1141]].

[[hz/40]] is closest to [[D#1]] at [[40]] Hz (+49 cents).

Note class: [[D#]], Octave: [[octave/1]].

• [[square]]: 1600

• [[square root]]: 6.3246

• [[cube]]: 64000

• [[cube root]]: 3.4200

• [[natural log]] (ln): 3.6889

• [[base-10 log]] (log10): 1.6021

• [[base-2 log]] (log2): 5.3219