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

Factor pairs: [[2]] * [[200]], [[4]] * [[100]], [[5]] * [[80]], [[8]] * [[50]], [[10]] * [[40]], [[16]] * [[25]], [[20]] * [[20]]

Prime neighborhood: [[383]], [[389]], [[397]], [[400]], [[401]], [[409]], [[419]]

Prime gap: 4 (interval [[397]] to [[401]])

Primes up to 400: [[2]], [[3]], [[5]], [[7]], [[11]], [[13]], [[17]], [[19]], [[23]], [[29]], [[31]], [[37]], [[41]], [[43]], [[47]], [[53]], [[59]], [[61]], [[67]], [[71]], [[73]], [[79]], [[83]], [[89]], [[97]], [[101]], [[103]], [[107]], [[109]], [[113]], [[127]], [[131]], [[137]], [[139]], [[149]], [[151]], [[157]], [[163]], [[167]], [[173]], [[179]], [[181]], [[191]], [[193]], [[197]], [[199]], [[211]], [[223]], [[227]], [[229]], [[233]], [[239]], [[241]], [[251]], [[257]], [[263]], [[269]], [[271]], [[277]], [[281]], [[283]], [[293]], [[307]], [[311]], [[313]], [[317]], [[331]], [[337]], [[347]], [[349]], [[353]], [[359]], [[367]], [[373]], [[379]], [[383]], [[389]], [[397]] (78 total).

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

The closest centered hexagonal numbers are [[397]] (index # [[12]]) and [[469]] (index # [[13]]).

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/400]] is closest to [[G4]] at [[400]] Hz (+35 cents).

Note class: [[G]], Octave: [[octave/4]].

• [[square]]: 160000

• [[square root]]: 20.0000

• [[cube]]: 64000000

• [[cube root]]: 7.3681

• [[natural log]] (ln): 5.9915

• [[base-10 log]] (log10): 2.6021

• [[base-2 log]] (log2): 8.6439