13315511981 has 2 divisors, whose sum is σ = 13315511982. Its totient is φ = 13315511980.

The previous prime is 13315511971. The next prime is 13315512013. The reversal of 13315511981 is 18911551331.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10956855625 + 2358656356 = 104675^2 + 48566^2 .

It is a cyclic number.

It is not a de Polignac number, because 13315511981 - 2⁶ = 13315511917 is a prime.

It is a super-2 number, since 2×13315511981² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13315511971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6657755990 + 6657755991.

It is an arithmetic number, because the mean of its divisors is an integer number (6657755991).

Almost surely, 2^13315511981 is an apocalyptic number.

It is an amenable number.

13315511981 is a deficient number, since it is larger than the sum of its proper divisors (1).

13315511981 is an equidigital number, since it uses as much as digits as its factorization.

13315511981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 38.

The spelling of 13315511981 in words is "thirteen billion, three hundred fifteen million, five hundred eleven thousand, nine hundred eighty-one".