81636057811969 has 2 divisors, whose sum is σ = 81636057811970. Its totient is φ = 81636057811968.

The previous prime is 81636057811961. The next prime is 81636057811991. The reversal of 81636057811969 is 96911875063618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 58554634410000 + 23081423401969 = 7652100^2 + 4804313^2 .

It is a cyclic number.

It is not a de Polignac number, because 81636057811969 - 2³ = 81636057811961 is a prime.

It is a super-2 number, since 2×81636057811969² (a number of 29 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81636057811898 and 81636057811907.

It is not a weakly prime, because it can be changed into another prime (81636057811961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40818028905984 + 40818028905985.

It is an arithmetic number, because the mean of its divisors is an integer number (40818028905985).

Almost surely, 2^{81636057811969} is an apocalyptic number.

It is an amenable number.

81636057811969 is a deficient number, since it is larger than the sum of its proper divisors (1).

81636057811969 is an equidigital number, since it uses as much as digits as its factorization.

81636057811969 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 117573120, while the sum is 70.

The spelling of 81636057811969 in words is "eighty-one trillion, six hundred thirty-six billion, fifty-seven million, eight hundred eleven thousand, nine hundred sixty-nine".