645893521 has 16 divisors (see below), whose sum is σ = 829511424. Its totient is φ = 488816064.

The previous prime is 645893513. The next prime is 645893527. The reversal of 645893521 is 125398546.

It is a cyclic number.

It is not a de Polignac number, because 645893521 - 2³ = 645893513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645893527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 152206 + ... + 156391.

It is an arithmetic number, because the mean of its divisors is an integer number (51844464).

Almost surely, 2^645893521 is an apocalyptic number.

It is an amenable number.

645893521 is a deficient number, since it is larger than the sum of its proper divisors (183617903).

645893521 is a wasteful number, since it uses less digits than its factorization.

645893521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308640.

The product of its digits is 259200, while the sum is 43.

The square root of 645893521 is about 25414.4352878438. The cubic root of 645893521 is about 864.4110488572.

The spelling of 645893521 in words is "six hundred forty-five million, eight hundred ninety-three thousand, five hundred twenty-one".