13121947681 has 2 divisors, whose sum is σ = 13121947682. Its totient is φ = 13121947680.

The previous prime is 13121947673. The next prime is 13121947691. The reversal of 13121947681 is 18674912131.

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., 8182107025 + 4939840656 = 90455^2 + 70284^2 .

It is a cyclic number.

It is not a de Polignac number, because 13121947681 - 2³ = 13121947673 is a prime.

It is a super-2 number, since 2×13121947681² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (13121947691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6560973840 + 6560973841.

It is an arithmetic number, because the mean of its divisors is an integer number (6560973841).

Almost surely, 2^13121947681 is an apocalyptic number.

It is an amenable number.

13121947681 is a deficient number, since it is larger than the sum of its proper divisors (1).

13121947681 is an equidigital number, since it uses as much as digits as its factorization.

13121947681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 43.

The spelling of 13121947681 in words is "thirteen billion, one hundred twenty-one million, nine hundred forty-seven thousand, six hundred eighty-one".