639395904 has 280 divisors, whose sum is σ = 2105903840. Its totient is φ = 170698752.

The previous prime is 639395899. The next prime is 639395909. The reversal of 639395904 is 409593936.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (639395899) and next prime (639395909).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (639395909) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 8758812 + ... + 8758884.

Almost surely, 2^639395904 is an apocalyptic number.

639395904 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639395904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1052951920).

639395904 is an abundant number, since it is smaller than the sum of its proper divisors (1466507936).

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

639395904 is an equidigital number, since it uses as much as digits as its factorization.

639395904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135 (or 104 counting only the distinct ones).

The product of its (nonzero) digits is 787320, while the sum is 48.

The square root of 639395904 is about 25286.2789670604. The cubic root of 639395904 is about 861.5026478702.

The spelling of 639395904 in words is "six hundred thirty-nine million, three hundred ninety-five thousand, nine hundred four".