21861311637 has 20 divisors (see below), whose sum is σ = 32063122400. Its totient is φ = 13249253160.

The previous prime is 21861311629. The next prime is 21861311683. The reversal of 21861311637 is 73611316812.

It is not a de Polignac number, because 21861311637 - 2³ = 21861311629 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21861311595 and 21861311604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861311627) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 204937 + ... + 292782.

It is an arithmetic number, because the mean of its divisors is an integer number (1603156120).

Almost surely, 2^21861311637 is an apocalyptic number.

It is an amenable number.

21861311637 is a deficient number, since it is larger than the sum of its proper divisors (10201810763).

21861311637 is an frugal number, since it uses more digits than its factorization.

21861311637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497766 (or 497733 counting only the distinct ones).

The product of its digits is 36288, while the sum is 39.

The spelling of 21861311637 in words is "twenty-one billion, eight hundred sixty-one million, three hundred eleven thousand, six hundred thirty-seven".