645789720 has 32 divisors (see below), whose sum is σ = 1937369520. Its totient is φ = 172210560.

The previous prime is 645789707. The next prime is 645789731. The reversal of 645789720 is 27987546.

It is a self number, because there is not a number n which added to its sum of digits gives 645789720.

It is a congruent number.

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, 2690671 + ... + 2690910.

Almost surely, 2^645789720 is an apocalyptic number.

645789720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645789720 is an abundant number, since it is smaller than the sum of its proper divisors (1291579800).

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

645789720 is a wasteful number, since it uses less digits than its factorization.

645789720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5381595 (or 5381591 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 48.

The square root of 645789720 is about 25412.3930396175. The cubic root of 645789720 is about 864.3647401209.

The spelling of 645789720 in words is "six hundred forty-five million, seven hundred eighty-nine thousand, seven hundred twenty".