21031131232021 has 4 divisors (see below), whose sum is σ = 21031572563200. Its totient is φ = 21030689900844.

The previous prime is 21031131231949. The next prime is 21031131232039. The reversal of 21031131232021 is 12023213113012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21031131232021 - 2¹³ = 21031131223829 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21031131231983 and 21031131232001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031131242021) 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, 220594101 + ... + 220689418.

It is an arithmetic number, because the mean of its divisors is an integer number (5257893140800).

Almost surely, 2^{21031131232021} is an apocalyptic number.

It is an amenable number.

21031131232021 is a deficient number, since it is larger than the sum of its proper divisors (441331179).

21031131232021 is an equidigital number, since it uses as much as digits as its factorization.

21031131232021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441331178.

The product of its (nonzero) digits is 432, while the sum is 22.

Adding to 21031131232021 its reverse (12023213113012), we get a palindrome (33054344345033).

The spelling of 21031131232021 in words is "twenty-one trillion, thirty-one billion, one hundred thirty-one million, two hundred thirty-two thousand, twenty-one".