640015625 has 14 divisors (see below), whose sum is σ = 800028822. Its totient is φ = 512000000.

The previous prime is 640015619. The next prime is 640015633. The reversal of 640015625 is 526510046.

It can be written as a sum of positive squares in 7 ways, for example, as 613255696 + 26759929 = 24764^2 + 5173^2 .

It is a sliding number, since 640015625 = 15625 + 640000000 and 1/15625 + 1/640000000 = 0.0000640015625.

It is not a de Polignac number, because 640015625 - 2¹⁶ = 639950089 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 4856 + ... + 36105.

Almost surely, 2^640015625 is an apocalyptic number.

It is an amenable number.

640015625 is a deficient number, since it is larger than the sum of its proper divisors (160013197).

640015625 is an frugal number, since it uses more digits than its factorization.

640015625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40991 (or 40966 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 640015625 is about 25298.5300956399. The cubic root of 640015625 is about 861.7808890894.

It can be divided in two parts, 6400 and 15625, that multiplied together give a 8-th power (100000000 = 10⁸).

The spelling of 640015625 in words is "six hundred forty million, fifteen thousand, six hundred twenty-five".