645123120 has 80 divisors (see below), whose sum is σ = 2053960800. Its totient is φ = 167380992.

The previous prime is 645123107. The next prime is 645123137. The reversal of 645123120 is 21321546.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

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, 27445 + ... + 45204.

It is an arithmetic number, because the mean of its divisors is an integer number (25674510).

Almost surely, 2^645123120 is an apocalyptic number.

645123120 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645123120 is an abundant number, since it is smaller than the sum of its proper divisors (1408837680).

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

645123120 is a wasteful number, since it uses less digits than its factorization.

645123120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72702 (or 72696 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 645123120 is about 25399.2740053727. The cubic root of 645123120 is about 864.0672315653.

Adding to 645123120 its reverse (21321546), we get a palindrome (666444666).

The spelling of 645123120 in words is "six hundred forty-five million, one hundred twenty-three thousand, one hundred twenty".