400387681 has 4 divisors (see below), whose sum is σ = 400561200. Its totient is φ = 400214164.

The previous prime is 400387679. The next prime is 400387709. The reversal of 400387681 is 186783004.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 400387681 - 2¹ = 400387679 is a prime.

It is a super-2 number, since 2×400387681² = 320620590193115522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 400387681.

It is not an unprimeable number, because it can be changed into a prime (400387651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 83251 + ... + 87928.

It is an arithmetic number, because the mean of its divisors is an integer number (100140300).

Almost surely, 2^400387681 is an apocalyptic number.

It is an amenable number.

400387681 is a deficient number, since it is larger than the sum of its proper divisors (173519).

400387681 is a wasteful number, since it uses less digits than its factorization.

400387681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173518.

The product of its (nonzero) digits is 32256, while the sum is 37.

The square root of 400387681 is about 20009.6896777536. The cubic root of 400387681 is about 737.0442610363.

The spelling of 400387681 in words is "four hundred million, three hundred eighty-seven thousand, six hundred eighty-one".