21312011321 has 2 divisors, whose sum is σ = 21312011322. Its totient is φ = 21312011320.

The previous prime is 21312011249. The next prime is 21312011363. The reversal of 21312011321 is 12311021312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21228490000 + 83521321 = 145700^2 + 9139^2 .

It is a cyclic number.

It is not a de Polignac number, because 21312011321 - 2¹⁰ = 21312010297 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21312011321.

It is not a weakly prime, because it can be changed into another prime (21312011381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656005660 + 10656005661.

It is an arithmetic number, because the mean of its divisors is an integer number (10656005661).

Almost surely, 2^21312011321 is an apocalyptic number.

It is an amenable number.

21312011321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312011321 is an equidigital number, since it uses as much as digits as its factorization.

21312011321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21312011321 its reverse (12311021312), we get a palindrome (33623032633).

Subtracting from 21312011321 its reverse (12311021312), we obtain a palindrome (9000990009).

The spelling of 21312011321 in words is "twenty-one billion, three hundred twelve million, eleven thousand, three hundred twenty-one".