21312312231 has 16 divisors (see below), whose sum is σ = 32586753024. Its totient is φ = 12136895904.

The previous prime is 21312312227. The next prime is 21312312239. The reversal of 21312312231 is 13221321312.

It is not a de Polignac number, because 21312312231 - 2² = 21312312227 is a prime.

It is a super-2 number, since 2×21312312231² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21312312198 and 21312312207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312312239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1725711 + ... + 1738016.

It is an arithmetic number, because the mean of its divisors is an integer number (2036672064).

Almost surely, 2^21312312231 is an apocalyptic number.

21312312231 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21312312231 is a deficient number, since it is larger than the sum of its proper divisors (11274440793).

21312312231 is a wasteful number, since it uses less digits than its factorization.

21312312231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3464030.

The product of its digits is 432, while the sum is 21.

Adding to 21312312231 its reverse (13221321312), we get a palindrome (34533633543).

The spelling of 21312312231 in words is "twenty-one billion, three hundred twelve million, three hundred twelve thousand, two hundred thirty-one".