639494940 has 48 divisors (see below), whose sum is σ = 2046385152. Its totient is φ = 146170176.

The previous prime is 639494927. The next prime is 639494959. The reversal of 639494940 is 49494936.

It is a self number, because there is not a number n which added to its sum of digits gives 639494940.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 760884 + ... + 761723.

It is an arithmetic number, because the mean of its divisors is an integer number (42633024).

Almost surely, 2^639494940 is an apocalyptic number.

639494940 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

639494940 is an abundant number, since it is smaller than the sum of its proper divisors (1406890212).

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

639494940 is a wasteful number, since it uses less digits than its factorization.

639494940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1522626 (or 1522624 counting only the distinct ones).

The product of its (nonzero) digits is 839808, while the sum is 48.

The square root of 639494940 is about 25288.2371864865. The cubic root of 639494940 is about 861.5471249415.

The spelling of 639494940 in words is "six hundred thirty-nine million, four hundred ninety-four thousand, nine hundred forty".