645539924 has 12 divisors (see below), whose sum is σ = 1153731264. Its totient is φ = 315902424.

The previous prime is 645539911. The next prime is 645539927. The reversal of 645539924 is 429935546.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645539927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1716674 + ... + 1717049.

It is an arithmetic number, because the mean of its divisors is an integer number (96144272).

Almost surely, 2^645539924 is an apocalyptic number.

It is an amenable number.

645539924 is a deficient number, since it is larger than the sum of its proper divisors (508191340).

645539924 is a wasteful number, since it uses less digits than its factorization.

645539924 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3433774 (or 3433772 counting only the distinct ones).

The product of its digits is 1166400, while the sum is 47.

The square root of 645539924 is about 25407.4777181837. The cubic root of 645539924 is about 864.2532782972.

The spelling of 645539924 in words is "six hundred forty-five million, five hundred thirty-nine thousand, nine hundred twenty-four".