16517518921 has 8 divisors (see below), whose sum is σ = 17446863104. Its totient is φ = 15612957360.

The previous prime is 16517518909. The next prime is 16517518973. The reversal of 16517518921 is 12981571561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16517518921 - 2⁵ = 16517518889 is a prime.

It is the 128521-st Hogben number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16517518321) by changing a digit.

It is a nontrivial repunit in base 128520.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6194286 + ... + 6196951.

It is an arithmetic number, because the mean of its divisors is an integer number (2180857888).

Almost surely, 2^16517518921 is an apocalyptic number.

It is an amenable number.

16517518921 is a deficient number, since it is larger than the sum of its proper divisors (929344183).

16517518921 is a wasteful number, since it uses less digits than its factorization.

16517518921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12391311.

The product of its digits is 151200, while the sum is 46.

The spelling of 16517518921 in words is "sixteen billion, five hundred seventeen million, five hundred eighteen thousand, nine hundred twenty-one".