640268931 has 16 divisors (see below), whose sum is σ = 883906560. Its totient is φ = 411764640.

The previous prime is 640268899. The next prime is 640268933. The reversal of 640268931 is 139862046.

It is not a de Polignac number, because 640268931 - 2⁵ = 640268899 is a prime.

It is a super-2 number, since 2×640268931² = 819888608007765522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 640268931.

It is not an unprimeable number, because it can be changed into a prime (640268933) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 125476 + ... + 130478.

It is an arithmetic number, because the mean of its divisors is an integer number (55244160).

Almost surely, 2^640268931 is an apocalyptic number.

640268931 is a deficient number, since it is larger than the sum of its proper divisors (243637629).

640268931 is a wasteful number, since it uses less digits than its factorization.

640268931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6506.

The product of its (nonzero) digits is 62208, while the sum is 39.

The square root of 640268931 is about 25303.5359386786. The cubic root of 640268931 is about 861.8945662502.

The spelling of 640268931 in words is "six hundred forty million, two hundred sixty-eight thousand, nine hundred thirty-one".