616665021 has 64 divisors (see below), whose sum is σ = 1028966400. Its totient is φ = 321608448.

The previous prime is 616665011. The next prime is 616665037. The reversal of 616665021 is 120566616.

It is not a de Polignac number, because 616665021 - 2⁹ = 616664509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (616665001) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4436370 + ... + 4436508.

It is an arithmetic number, because the mean of its divisors is an integer number (16077600).

Almost surely, 2^616665021 is an apocalyptic number.

It is an amenable number.

616665021 is a deficient number, since it is larger than the sum of its proper divisors (412301379).

616665021 is a wasteful number, since it uses less digits than its factorization.

616665021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243 (or 209 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 616665021 is about 24832.7409079223. The cubic root of 616665021 is about 851.1702547553.

The spelling of 616665021 in words is "six hundred sixteen million, six hundred sixty-five thousand, twenty-one".