640634400 has 576 divisors, whose sum is σ = 2799820800. Its totient is φ = 138101760.

The previous prime is 640634363. The next prime is 640634413. The reversal of 640634400 is 4436046.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2872689 + ... + 2872911.

It is an arithmetic number, because the mean of its divisors is an integer number (4860800).

Almost surely, 2^640634400 is an apocalyptic number.

640634400 is a gapful number since it is divisible by the number (60) 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 640634400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1399910400).

640634400 is an abundant number, since it is smaller than the sum of its proper divisors (2159186400).

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

640634400 is a wasteful number, since it uses less digits than its factorization.

640634400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278 (or 259 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 27.

The square root of 640634400 is about 25310.7566066287. The cubic root of 640634400 is about 862.0585264318.

The spelling of 640634400 in words is "six hundred forty million, six hundred thirty-four thousand, four hundred".