645123501 has 32 divisors (see below), whose sum is σ = 1047066240. Its totient is φ = 389318400.

The previous prime is 645123487. The next prime is 645123509. The reversal of 645123501 is 105321546.

645123501 is a `hidden beast` number, since 645 + 12 + 3 + 5 + 0 + 1 = 666.

It is not a de Polignac number, because 645123501 - 2²³ = 636734893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645123509) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 67071 + ... + 76083.

It is an arithmetic number, because the mean of its divisors is an integer number (32720820).

Almost surely, 2^645123501 is an apocalyptic number.

It is an amenable number.

645123501 is a deficient number, since it is larger than the sum of its proper divisors (401942739).

645123501 is a wasteful number, since it uses less digits than its factorization.

645123501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9274 (or 9268 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 645123501 is about 25399.2815055859. The cubic root of 645123501 is about 864.0674016669.

The spelling of 645123501 in words is "six hundred forty-five million, one hundred twenty-three thousand, five hundred one".