21331221023 has 4 divisors (see below), whose sum is σ = 24378538320. Its totient is φ = 18283903728.

The previous prime is 21331220983. The next prime is 21331221031. The reversal of 21331221023 is 32012213312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21331221023 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21331220986 and 21331221004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331241023) 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, 1523658638 + ... + 1523658651.

It is an arithmetic number, because the mean of its divisors is an integer number (6094634580).

Almost surely, 2^21331221023 is an apocalyptic number.

21331221023 is a deficient number, since it is larger than the sum of its proper divisors (3047317297).

21331221023 is an equidigital number, since it uses as much as digits as its factorization.

21331221023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3047317296.

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 21331221023 its reverse (32012213312), we get a palindrome (53343434335).

The spelling of 21331221023 in words is "twenty-one billion, three hundred thirty-one million, two hundred twenty-one thousand, twenty-three".