640692537 has 16 divisors (see below), whose sum is σ = 859508160. Its totient is φ = 424512000.

The previous prime is 640692523. The next prime is 640692539. The reversal of 640692537 is 735296046.

It is not a de Polignac number, because 640692537 - 2¹² = 640688441 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640692539) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 397389 + ... + 398997.

It is an arithmetic number, because the mean of its divisors is an integer number (53719260).

Almost surely, 2^640692537 is an apocalyptic number.

It is an amenable number.

640692537 is a deficient number, since it is larger than the sum of its proper divisors (218815623).

640692537 is a wasteful number, since it uses less digits than its factorization.

640692537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2344.

The product of its (nonzero) digits is 272160, while the sum is 42.

The square root of 640692537 is about 25311.9050448598. The cubic root of 640692537 is about 862.0846026569.

The spelling of 640692537 in words is "six hundred forty million, six hundred ninety-two thousand, five hundred thirty-seven".