21864635686 has 4 divisors (see below), whose sum is σ = 32796953532. Its totient is φ = 10932317842.

The previous prime is 21864635671. The next prime is 21864635693. The reversal of 21864635686 is 68653646812.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5466158920 + ... + 5466158923.

It is an arithmetic number, because the mean of its divisors is an integer number (8199238383).

Almost surely, 2^21864635686 is an apocalyptic number.

21864635686 is a deficient number, since it is larger than the sum of its proper divisors (10932317846).

21864635686 is a wasteful number, since it uses less digits than its factorization.

21864635686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10932317845.

The product of its digits is 9953280, while the sum is 55.

The spelling of 21864635686 in words is "twenty-one billion, eight hundred sixty-four million, six hundred thirty-five thousand, six hundred eighty-six".