81902029961 has 2 divisors, whose sum is σ = 81902029962. Its totient is φ = 81902029960.

The previous prime is 81902029933. The next prime is 81902029981. The reversal of 81902029961 is 16992020918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 63038655625 + 18863374336 = 251075^2 + 137344^2 .

It is a cyclic number.

It is not a de Polignac number, because 81902029961 - 2²⁶ = 81834921097 is a prime.

It is not a weakly prime, because it can be changed into another prime (81902029981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40951014980 + 40951014981.

It is an arithmetic number, because the mean of its divisors is an integer number (40951014981).

Almost surely, 2^81902029961 is an apocalyptic number.

It is an amenable number.

81902029961 is a deficient number, since it is larger than the sum of its proper divisors (1).

81902029961 is an equidigital number, since it uses as much as digits as its factorization.

81902029961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 139968, while the sum is 47.

The spelling of 81902029961 in words is "eighty-one billion, nine hundred two million, twenty-nine thousand, nine hundred sixty-one".