400640256 has 135 divisors (see below), whose sum is σ = 1203293091. Its totient is φ = 132585984.

The previous prime is 400640237. The next prime is 400640281. The reversal of 400640256 is 652046004.

It is a happy number.

The square root of 400640256 is 20016.

It is a perfect power (a square), and thus also a powerful number.

400640256 is a `hidden beast` number, since 400 + 6 + 4 + 0 + 256 = 666.

It is a super-2 number, since 2×400640256² = 321025229455491072, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nialpdrome in base 12.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 2882235 + ... + 2882373.

Almost surely, 2^400640256 is an apocalyptic number.

400640256 is the 20016-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 400640256

400640256 is an abundant number, since it is smaller than the sum of its proper divisors (802652835).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

400640256 is an frugal number, since it uses more digits than its factorization.

400640256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306 (or 144 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The cubic root of 400640256 is about 737.1992107114.

The spelling of 400640256 in words is "four hundred million, six hundred forty thousand, two hundred fifty-six".