645122621 has 16 divisors (see below), whose sum is σ = 760148928. Its totient is φ = 539760000.

The previous prime is 645122609. The next prime is 645122627. The reversal of 645122621 is 126221546.

It is not a de Polignac number, because 645122621 - 2⁶ = 645122557 is a prime.

It is a super-2 number, since 2×645122621² = 832366392251819282, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645122627) 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, 43121 + ... + 56121.

It is an arithmetic number, because the mean of its divisors is an integer number (47509308).

Almost surely, 2^645122621 is an apocalyptic number.

It is an amenable number.

645122621 is a deficient number, since it is larger than the sum of its proper divisors (115026307).

645122621 is a wasteful number, since it uses less digits than its factorization.

645122621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13372.

The product of its digits is 5760, while the sum is 29.

The square root of 645122621 is about 25399.2641822554. The cubic root of 645122621 is about 864.0670087811.

The spelling of 645122621 in words is "six hundred forty-five million, one hundred twenty-two thousand, six hundred twenty-one".