640991080 has 16 divisors (see below), whose sum is σ = 1442230020. Its totient is φ = 256396416.

The previous prime is 640991059. The next prime is 640991093. The reversal of 640991080 is 80199046.

It can be written as a sum of positive squares in 2 ways, for example, as 622103364 + 18887716 = 24942^2 + 4346^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8012349 + ... + 8012428.

Almost surely, 2^640991080 is an apocalyptic number.

It is an amenable number.

640991080 is an abundant number, since it is smaller than the sum of its proper divisors (801238940).

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

640991080 is a wasteful number, since it uses less digits than its factorization.

640991080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16024788 (or 16024784 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 640991080 is about 25317.8016423227. The cubic root of 640991080 is about 862.2184834935.

It can be divided in two parts, 6409910 and 80, that added together give a triangular number (6409990 = T₃₅₈₀).

The spelling of 640991080 in words is "six hundred forty million, nine hundred ninety-one thousand, eighty".