639953440 has 384 divisors, whose sum is σ = 2024870400. Its totient is φ = 185794560.

The previous prime is 639953401. The next prime is 639953467. The reversal of 639953440 is 44359936.

639953440 = 231² + 232² + ... + 1245².

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 10491010 + ... + 10491070.

It is an arithmetic number, because the mean of its divisors is an integer number (5273100).

Almost surely, 2^639953440 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 639953440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1012435200).

639953440 is an abundant number, since it is smaller than the sum of its proper divisors (1384916960).

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

639953440 is a wasteful number, since it uses less digits than its factorization.

639953440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 43.

The square root of 639953440 is about 25297.3010418108. The cubic root of 639953440 is about 861.7529774895.

The spelling of 639953440 in words is "six hundred thirty-nine million, nine hundred fifty-three thousand, four hundred forty".