21921635686 has 8 divisors (see below), whose sum is σ = 32883112944. Its totient is φ = 10960598040.

The previous prime is 21921635663. The next prime is 21921635693. The reversal of 21921635686 is 68653612912.

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

It is a super-2 number, since 2×21921635686² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81276 + ... + 224608.

It is an arithmetic number, because the mean of its divisors is an integer number (4110389118).

Almost surely, 2^21921635686 is an apocalyptic number.

21921635686 is a deficient number, since it is larger than the sum of its proper divisors (10961477258).

21921635686 is a wasteful number, since it uses less digits than its factorization.

21921635686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219806.

The product of its digits is 933120, while the sum is 49.

The spelling of 21921635686 in words is "twenty-one billion, nine hundred twenty-one million, six hundred thirty-five thousand, six hundred eighty-six".