645664580 has 24 divisors (see below), whose sum is σ = 1479159360. Its totient is φ = 234787040.

The previous prime is 645664561. The next prime is 645664601. The reversal of 645664580 is 85466546.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1467200 + ... + 1467639.

It is an arithmetic number, because the mean of its divisors is an integer number (61631640).

Almost surely, 2^645664580 is an apocalyptic number.

It is an amenable number.

645664580 is an abundant number, since it is smaller than the sum of its proper divisors (833494780).

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

645664580 is a wasteful number, since it uses less digits than its factorization.

645664580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2934859 (or 2934857 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 44.

The square root of 645664580 is about 25409.9307358363. The cubic root of 645664580 is about 864.3089048194.

The spelling of 645664580 in words is "six hundred forty-five million, six hundred sixty-four thousand, five hundred eighty".