639349788 has 96 divisors (see below), whose sum is σ = 1910297088. Its totient is φ = 161568000.

The previous prime is 639349693. The next prime is 639349793. The reversal of 639349788 is 887943936.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24838 + ... + 43538.

It is an arithmetic number, because the mean of its divisors is an integer number (19898928).

Almost surely, 2^639349788 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639349788, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (955148544).

639349788 is an abundant number, since it is smaller than the sum of its proper divisors (1270947300).

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

639349788 is a wasteful number, since it uses less digits than its factorization.

639349788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18763 (or 18761 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 57.

The square root of 639349788 is about 25285.3670726766. The cubic root of 639349788 is about 861.4819356057.

The spelling of 639349788 in words is "six hundred thirty-nine million, three hundred forty-nine thousand, seven hundred eighty-eight".