645235521 has 16 divisors (see below), whose sum is σ = 986962944. Its totient is φ = 367300944.

The previous prime is 645235501. The next prime is 645235523. The reversal of 645235521 is 125532546.

It is a de Polignac number, because none of the positive numbers 2^k-645235521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645235523) 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 15 ways as a sum of consecutive naturals, for example, 52891 + ... + 63936.

It is an arithmetic number, because the mean of its divisors is an integer number (61685184).

Almost surely, 2^645235521 is an apocalyptic number.

It is an amenable number.

645235521 is a deficient number, since it is larger than the sum of its proper divisors (341727423).

645235521 is a wasteful number, since it uses less digits than its factorization.

645235521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117100.

The product of its digits is 36000, while the sum is 33.

The square root of 645235521 is about 25401.4865903553. The cubic root of 645235521 is about 864.1174113309.

The spelling of 645235521 in words is "six hundred forty-five million, two hundred thirty-five thousand, five hundred twenty-one".