12311021981 has 2 divisors, whose sum is σ = 12311021982. Its totient is φ = 12311021980.

The previous prime is 12311021963. The next prime is 12311022011. The reversal of 12311021981 is 18912011321.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12187056025 + 123965956 = 110395^2 + 11134^2 .

It is a cyclic number.

It is not a de Polignac number, because 12311021981 - 2¹⁰ = 12311020957 is a prime.

It is a super-2 number, since 2×12311021981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12311021081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6155510990 + 6155510991.

It is an arithmetic number, because the mean of its divisors is an integer number (6155510991).

Almost surely, 2^12311021981 is an apocalyptic number.

It is an amenable number.

12311021981 is a deficient number, since it is larger than the sum of its proper divisors (1).

12311021981 is an equidigital number, since it uses as much as digits as its factorization.

12311021981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 29.

The spelling of 12311021981 in words is "twelve billion, three hundred eleven million, twenty-one thousand, nine hundred eighty-one".