15616996921 has 4 divisors (see below), whose sum is σ = 15618207312. Its totient is φ = 15615786532.

The previous prime is 15616996919. The next prime is 15616996937. The reversal of 15616996921 is 12969961651.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 15616996921 - 2¹ = 15616996919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15616996951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 585631 + ... + 611716.

It is an arithmetic number, because the mean of its divisors is an integer number (3904551828).

Almost surely, 2^15616996921 is an apocalyptic number.

It is an amenable number.

15616996921 is a deficient number, since it is larger than the sum of its proper divisors (1210391).

15616996921 is a wasteful number, since it uses less digits than its factorization.

15616996921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1210390.

The product of its digits is 1574640, while the sum is 55.

The spelling of 15616996921 in words is "fifteen billion, six hundred sixteen million, nine hundred ninety-six thousand, nine hundred twenty-one".