21312311131 has 4 divisors (see below), whose sum is σ = 21313611072. Its totient is φ = 21311011192.

The previous prime is 21312311123. The next prime is 21312311161. The reversal of 21312311131 is 13111321312.

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 21312311131 - 2³ = 21312311123 is a prime.

It is a super-2 number, since 2×21312311131² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21312311099 and 21312311108.

It is not an unprimeable number, because it can be changed into a prime (21312311161) 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, 625060 + ... + 658273.

It is an arithmetic number, because the mean of its divisors is an integer number (5328402768).

Almost surely, 2^21312311131 is an apocalyptic number.

21312311131 is a deficient number, since it is larger than the sum of its proper divisors (1299941).

21312311131 is a wasteful number, since it uses less digits than its factorization.

21312311131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1299940.

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

Adding to 21312311131 its reverse (13111321312), we get a palindrome (34423632443).

The spelling of 21312311131 in words is "twenty-one billion, three hundred twelve million, three hundred eleven thousand, one hundred thirty-one".