640991200 has 72 divisors (see below), whose sum is σ = 1572274368. Its totient is φ = 255175680.

The previous prime is 640991191. The next prime is 640991249. The reversal of 640991200 is 2199046.

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 11 ways as a sum of consecutive naturals, for example, 176604 + ... + 180196.

It is an arithmetic number, because the mean of its divisors is an integer number (21837144).

Almost surely, 2^640991200 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 640991200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (786137184).

640991200 is an abundant number, since it is smaller than the sum of its proper divisors (931283168).

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

640991200 is a wasteful number, since it uses less digits than its factorization.

640991200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3836 (or 3823 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 640991200 is about 25317.8040121966. The cubic root of 640991200 is about 862.2185372988.

The spelling of 640991200 in words is "six hundred forty million, nine hundred ninety-one thousand, two hundred".