639974080 has 112 divisors (see below), whose sum is σ = 1609709760. Its totient is φ = 241860608.

The previous prime is 639974053. The next prime is 639974081. The reversal of 639974080 is 80479936.

It is a Harshad number since it is a multiple of its sum of digits (46).

It is a self number, because there is not a number n which added to its sum of digits gives 639974080.

It is not an unprimeable number, because it can be changed into a prime (639974081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 654552 + ... + 655528.

Almost surely, 2^639974080 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 639974080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (804854880).

639974080 is an abundant number, since it is smaller than the sum of its proper divisors (969735680).

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

639974080 is a wasteful number, since it uses less digits than its factorization.

639974080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1106 (or 1096 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 46.

The square root of 639974080 is about 25297.7089871791. The cubic root of 639974080 is about 861.7622419084.

The spelling of 639974080 in words is "six hundred thirty-nine million, nine hundred seventy-four thousand, eighty".