640682931 has 16 divisors (see below), whose sum is σ = 982502144. Its totient is φ = 363770784.

The previous prime is 640682923. The next prime is 640682941. The reversal of 640682931 is 139286046.

640682931 = T₁₅₄ + T₁₅₅ + ... + T₁₅₆₆.

It is not a de Polignac number, because 640682931 - 2³ = 640682923 is a prime.

It is a super-2 number, since 2×640682931² = 820949236149501522, 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 640682931.

It is not an unprimeable number, because it can be changed into a prime (640682941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 93865 + ... + 100458.

It is an arithmetic number, because the mean of its divisors is an integer number (61406384).

Almost surely, 2^640682931 is an apocalyptic number.

640682931 is a deficient number, since it is larger than the sum of its proper divisors (341819213).

640682931 is a wasteful number, since it uses less digits than its factorization.

640682931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194490.

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

The square root of 640682931 is about 25311.7152915404. The cubic root of 640682931 is about 862.0802941805.

The spelling of 640682931 in words is "six hundred forty million, six hundred eighty-two thousand, nine hundred thirty-one".