21311131123 has 4 divisors (see below), whose sum is σ = 21343372528. Its totient is φ = 21278889720.

The previous prime is 21311131111. The next prime is 21311131159. The reversal of 21311131123 is 32113111312.

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 21311131123 - 2²¹ = 21309033971 is a prime.

It is a super-2 number, since 2×21311131123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21311131123.

It is not an unprimeable number, because it can be changed into a prime (21311131103) 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, 16119711 + ... + 16121032.

It is an arithmetic number, because the mean of its divisors is an integer number (5335843132).

Almost surely, 2^21311131123 is an apocalyptic number.

21311131123 is a deficient number, since it is larger than the sum of its proper divisors (32241405).

21311131123 is an equidigital number, since it uses as much as digits as its factorization.

21311131123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32241404.

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

Adding to 21311131123 its reverse (32113111312), we get a palindrome (53424242435).

The spelling of 21311131123 in words is "twenty-one billion, three hundred eleven million, one hundred thirty-one thousand, one hundred twenty-three".