616642821 has 8 divisors (see below), whose sum is σ = 913544960. Its totient is φ = 411095196.

The previous prime is 616642801. The next prime is 616642823. The reversal of 616642821 is 128246616.

616642821 is a `hidden beast` number, since 6 + 1 + 6 + 642 + 8 + 2 + 1 = 666.

It is not a de Polignac number, because 616642821 - 2¹⁰ = 616641797 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (616642823) 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 7 ways as a sum of consecutive naturals, for example, 11419285 + ... + 11419338.

It is an arithmetic number, because the mean of its divisors is an integer number (114193120).

Almost surely, 2^616642821 is an apocalyptic number.

It is an amenable number.

616642821 is a deficient number, since it is larger than the sum of its proper divisors (296902139).

616642821 is a wasteful number, since it uses less digits than its factorization.

616642821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22838632 (or 22838626 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 616642821 is about 24832.2939133701. The cubic root of 616642821 is about 851.1600405624.

The spelling of 616642821 in words is "six hundred sixteen million, six hundred forty-two thousand, eight hundred twenty-one".