640925 has 12 divisors (see below), whose sum is σ = 821376. Its totient is φ = 495600.

The previous prime is 640919. The next prime is 640933. The reversal of 640925 is 529046.

It is not a de Polignac number, because 640925 - 2⁸ = 640669 is a prime.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 640894 and 640903.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640925.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 362 + ... + 1188.

It is an arithmetic number, because the mean of its divisors is an integer number (68448).

2⁶⁴⁰⁹²⁵ is an apocalyptic number.

It is an amenable number.

640925 is a deficient number, since it is larger than the sum of its proper divisors (180451).

640925 is a wasteful number, since it uses less digits than its factorization.

640925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 868 (or 863 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 640925 is about 800.5779162580. The cubic root of 640925 is about 86.2188853671.

The spelling of 640925 in words is "six hundred forty thousand, nine hundred twenty-five".