640808564 has 24 divisors (see below), whose sum is σ = 1262827776. Its totient is φ = 281880000.

The previous prime is 640808551. The next prime is 640808603. The reversal of 640808564 is 465808046.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 233537 + ... + 236264.

It is an arithmetic number, because the mean of its divisors is an integer number (52617824).

Almost surely, 2^640808564 is an apocalyptic number.

It is an amenable number.

640808564 is a deficient number, since it is larger than the sum of its proper divisors (622019212).

640808564 is a wasteful number, since it uses less digits than its factorization.

640808564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 469847 (or 469845 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 41.

The square root of 640808564 is about 25314.1968863324. The cubic root of 640808564 is about 862.1366396049.

The spelling of 640808564 in words is "six hundred forty million, eight hundred eight thousand, five hundred sixty-four".