400039999 has 2 divisors, whose sum is σ = 400040000. Its totient is φ = 400039998.

The previous prime is 400039987. The next prime is 400040021. The reversal of 400039999 is 999930004.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 400039999 - 2²³ = 391651391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400039099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200019999 + 200020000.

It is an arithmetic number, because the mean of its divisors is an integer number (200020000).

Almost surely, 2^400039999 is an apocalyptic number.

400039999 is a deficient number, since it is larger than the sum of its proper divisors (1).

400039999 is an equidigital number, since it uses as much as digits as its factorization.

400039999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 78732, while the sum is 43.

The square root of 400039999 is about 20000.9999500025. Note that the first 4 decimals coincide. The cubic root of 400039999 is about 736.8308585055.

The spelling of 400039999 in words is "four hundred million, thirty-nine thousand, nine hundred ninety-nine".