21687166885 has 8 divisors (see below), whose sum is σ = 26044766496. Its totient is φ = 17336289360.

The previous prime is 21687166871. The next prime is 21687166913. The reversal of 21687166885 is 58866178612.

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

It is not a de Polignac number, because 21687166885 - 2⁷ = 21687166757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1673419 + ... + 1686328.

It is an arithmetic number, because the mean of its divisors is an integer number (3255595812).

Almost surely, 2^21687166885 is an apocalyptic number.

It is an amenable number.

21687166885 is a deficient number, since it is larger than the sum of its proper divisors (4357599611).

21687166885 is a wasteful number, since it uses less digits than its factorization.

21687166885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3361043.

The product of its digits is 7741440, while the sum is 58.

The spelling of 21687166885 in words is "twenty-one billion, six hundred eighty-seven million, one hundred sixty-six thousand, eight hundred eighty-five".