400978399 has 2 divisors, whose sum is σ = 400978400. Its totient is φ = 400978398.

The previous prime is 400978381. The next prime is 400978421. The reversal of 400978399 is 993879004.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 400978399 - 2⁵ = 400978367 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400978379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200489199 + 200489200.

It is an arithmetic number, because the mean of its divisors is an integer number (200489200).

Almost surely, 2^400978399 is an apocalyptic number.

400978399 is a deficient number, since it is larger than the sum of its proper divisors (1).

400978399 is an equidigital number, since it uses as much as digits as its factorization.

400978399 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 489888, while the sum is 49.

The square root of 400978399 is about 20024.4450360054. The cubic root of 400978399 is about 737.4065527104.

The spelling of 400978399 in words is "four hundred million, nine hundred seventy-eight thousand, three hundred ninety-nine".