645231720 has 64 divisors (see below), whose sum is σ = 2212225920. Its totient is φ = 147481344.

The previous prime is 645231683. The next prime is 645231767. The reversal of 645231720 is 27132546.

645231720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 383227 + ... + 384906.

It is an arithmetic number, because the mean of its divisors is an integer number (34566030).

Almost surely, 2^645231720 is an apocalyptic number.

645231720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645231720 is an abundant number, since it is smaller than the sum of its proper divisors (1566994200).

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

645231720 is a wasteful number, since it uses less digits than its factorization.

645231720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 768154 (or 768150 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 30.

The square root of 645231720 is about 25401.4117717894. The cubic root of 645231720 is about 864.1157145258.

The spelling of 645231720 in words is "six hundred forty-five million, two hundred thirty-one thousand, seven hundred twenty".