21123131113 has 4 divisors (see below), whose sum is σ = 24140721280. Its totient is φ = 18105540948.

The previous prime is 21123131083. The next prime is 21123131147. The reversal of 21123131113 is 31113132112.

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 21123131113 - 2³³ = 12533196521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123131173) 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, 1508795073 + ... + 1508795086.

It is an arithmetic number, because the mean of its divisors is an integer number (6035180320).

Almost surely, 2^21123131113 is an apocalyptic number.

It is an amenable number.

21123131113 is a deficient number, since it is larger than the sum of its proper divisors (3017590167).

21123131113 is an equidigital number, since it uses as much as digits as its factorization.

21123131113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3017590166.

The product of its digits is 108, while the sum is 19.

Adding to 21123131113 its reverse (31113132112), we get a palindrome (52236263225).

Subtracting 21123131113 from its reverse (31113132112), we obtain a palindrome (9990000999).

The spelling of 21123131113 in words is "twenty-one billion, one hundred twenty-three million, one hundred thirty-one thousand, one hundred thirteen".