640247856 has 40 divisors (see below), whose sum is σ = 1655132160. Its totient is φ = 213266496.

The previous prime is 640247843. The next prime is 640247869. The reversal of 640247856 is 658742046.

It is an interprime number because it is at equal distance from previous prime (640247843) and next prime (640247869).

It is a super-2 number, since 2×640247856² = 819834634225193472, which contains 22 as substring.

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 7 ways as a sum of consecutive naturals, for example, 80641 + ... + 88223.

It is an arithmetic number, because the mean of its divisors is an integer number (41378304).

Almost surely, 2^640247856 is an apocalyptic number.

It is an amenable number.

640247856 is an abundant number, since it is smaller than the sum of its proper divisors (1014884304).

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

640247856 is a wasteful number, since it uses less digits than its factorization.

640247856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9353 (or 9347 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 42.

The square root of 640247856 is about 25303.1194914777. The cubic root of 640247856 is about 861.8851094806.

The spelling of 640247856 in words is "six hundred forty million, two hundred forty-seven thousand, eight hundred fifty-six".