639693520 has 40 divisors (see below), whose sum is σ = 1565569440. Its totient is φ = 242409600.

The previous prime is 639693497. The next prime is 639693529. The reversal of 639693520 is 25396936.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639693529) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 208906 + ... + 211945.

It is an arithmetic number, because the mean of its divisors is an integer number (39139236).

Almost surely, 2^639693520 is an apocalyptic number.

It is an amenable number.

639693520 is an abundant number, since it is smaller than the sum of its proper divisors (925875920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639693520 is a wasteful number, since it uses less digits than its factorization.

639693520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420883 (or 420877 counting only the distinct ones).

The product of its (nonzero) digits is 262440, while the sum is 43.

The square root of 639693520 is about 25292.1632131378. The cubic root of 639693520 is about 861.6362933938.

The spelling of 639693520 in words is "six hundred thirty-nine million, six hundred ninety-three thousand, five hundred twenty".