645522624021561 has 48 divisors (see below), whose sum is σ = 1016731303267392. Its totient is φ = 361129006368000.

The previous prime is 645522624021529. The next prime is 645522624021577. The reversal of 645522624021561 is 165120426225546.

It is not a de Polignac number, because 645522624021561 - 2⁵ = 645522624021529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645522624021661) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1029719511 + ... + 1030346211.

It is an arithmetic number, because the mean of its divisors is an integer number (21181902151404).

Almost surely, 2^{645522624021561} is an apocalyptic number.

It is an amenable number.

645522624021561 is a deficient number, since it is larger than the sum of its proper divisors (371208679245831).

645522624021561 is a wasteful number, since it uses less digits than its factorization.

645522624021561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 811434 (or 811421 counting only the distinct ones).

The product of its (nonzero) digits is 6912000, while the sum is 51.

The spelling of 645522624021561 in words is "six hundred forty-five trillion, five hundred twenty-two billion, six hundred twenty-four million, twenty-one thousand, five hundred sixty-one".