21793987231 has 4 divisors (see below), whose sum is σ = 21794988600. Its totient is φ = 21792985864.

The previous prime is 21793987223. The next prime is 21793987253. The reversal of 21793987231 is 13278939712.

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

It is a cyclic number.

It is not a de Polignac number, because 21793987231 - 2³ = 21793987223 is a prime.

It is a super-2 number, since 2×21793987231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21793987261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 467296 + ... + 511813.

It is an arithmetic number, because the mean of its divisors is an integer number (5448747150).

Almost surely, 2^21793987231 is an apocalyptic number.

21793987231 is a deficient number, since it is larger than the sum of its proper divisors (1001369).

21793987231 is an equidigital number, since it uses as much as digits as its factorization.

21793987231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1001368.

The product of its digits is 1143072, while the sum is 52.

The spelling of 21793987231 in words is "twenty-one billion, seven hundred ninety-three million, nine hundred eighty-seven thousand, two hundred thirty-one".