16668718521 has 32 divisors (see below), whose sum is σ = 27912057600. Its totient is φ = 8792284032.

The previous prime is 16668718511. The next prime is 16668718529. The reversal of 16668718521 is 12581786661.

It is not a de Polignac number, because 16668718521 - 2⁵ = 16668718489 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16668718529) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 609660 + ... + 636413.

It is an arithmetic number, because the mean of its divisors is an integer number (872251800).

Almost surely, 2^16668718521 is an apocalyptic number.

It is an amenable number.

16668718521 is a deficient number, since it is larger than the sum of its proper divisors (11243339079).

16668718521 is a wasteful number, since it uses less digits than its factorization.

16668718521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1246110 (or 1246096 counting only the distinct ones).

The product of its digits is 967680, while the sum is 51.

The spelling of 16668718521 in words is "sixteen billion, six hundred sixty-eight million, seven hundred eighteen thousand, five hundred twenty-one".