616645521 has 32 divisors (see below), whose sum is σ = 959078400. Its totient is φ = 391061520.

The previous prime is 616645493. The next prime is 616645529. The reversal of 616645521 is 125546616.

616645521 is a `hidden beast` number, since 6 + 1 + 6 + 645 + 5 + 2 + 1 = 666.

It is not a de Polignac number, because 616645521 - 2⁶ = 616645457 is a prime.

It is a super-2 number, since 2×616645521² = 760503397138722882, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (616645529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 43140 + ... + 55626.

It is an arithmetic number, because the mean of its divisors is an integer number (29971200).

Almost surely, 2^616645521 is an apocalyptic number.

It is an amenable number.

616645521 is a deficient number, since it is larger than the sum of its proper divisors (342432879).

616645521 is a wasteful number, since it uses less digits than its factorization.

616645521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12586 (or 12580 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 616645521 is about 24832.3482780022. The cubic root of 616645521 is about 851.1612828422.

The spelling of 616645521 in words is "six hundred sixteen million, six hundred forty-five thousand, five hundred twenty-one".