645587720 has 32 divisors (see below), whose sum is σ = 1453339800. Its totient is φ = 258098688.

The previous prime is 645587711. The next prime is 645587771. The reversal of 645587720 is 27785546.

It can be written as a sum of positive squares in 4 ways, for example, as 509585476 + 136002244 = 22574^2 + 11662^2 .

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, 110636 + ... + 116324.

Almost surely, 2^645587720 is an apocalyptic number.

It is an amenable number.

645587720 is an abundant number, since it is smaller than the sum of its proper divisors (807752080).

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

645587720 is a wasteful number, since it uses less digits than its factorization.

645587720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8537 (or 8533 counting only the distinct ones).

The product of its (nonzero) digits is 470400, while the sum is 44.

The square root of 645587720 is about 25408.4182900077. The cubic root of 645587720 is about 864.2746076417.

The spelling of 645587720 in words is "six hundred forty-five million, five hundred eighty-seven thousand, seven hundred twenty".