640239136 has 36 divisors (see below), whose sum is σ = 1279851678. Its totient is φ = 315270912.

The previous prime is 640239113. The next prime is 640239161. The reversal of 640239136 is 631932046.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 494795536 + 145443600 = 22244^2 + 12060^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 141420 + ... + 145876.

Almost surely, 2^640239136 is an apocalyptic number.

It is an amenable number.

640239136 is a deficient number, since it is larger than the sum of its proper divisors (639612542).

640239136 is an equidigital number, since it uses as much as digits as its factorization.

640239136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4601 (or 4526 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 34.

The square root of 640239136 is about 25302.9471801211. The cubic root of 640239136 is about 861.8811965833.

The spelling of 640239136 in words is "six hundred forty million, two hundred thirty-nine thousand, one hundred thirty-six".