21851131983 has 4 divisors (see below), whose sum is σ = 29134842648. Its totient is φ = 14567421320.

The previous prime is 21851131949. The next prime is 21851132011. The reversal of 21851131983 is 38913115812.

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 21851131983 - 2²⁰ = 21850083407 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851131483) 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, 3641855328 + ... + 3641855333.

It is an arithmetic number, because the mean of its divisors is an integer number (7283710662).

Almost surely, 2^21851131983 is an apocalyptic number.

21851131983 is a deficient number, since it is larger than the sum of its proper divisors (7283710665).

21851131983 is an equidigital number, since it uses as much as digits as its factorization.

21851131983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7283710664.

The product of its digits is 51840, while the sum is 42.

The spelling of 21851131983 in words is "twenty-one billion, eight hundred fifty-one million, one hundred thirty-one thousand, nine hundred eighty-three".