81565963421049 has 20 divisors (see below), whose sum is σ = 129012831034164. Its totient is φ = 51178643714304.

The previous prime is 81565963421011. The next prime is 81565963421099. The reversal of 81565963421049 is 94012436956518.

81565963421049 is a `hidden beast` number, since 8 + 1 + 5 + 6 + 596 + 34 + 2 + 1 + 0 + 4 + 9 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 62469343100025 + 19096620321024 = 7903755^2 + 4369968^2 .

It is not a de Polignac number, because 81565963421049 - 2⁹ = 81565963420537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81565963421099) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 29617269292 + ... + 29617272045.

Almost surely, 2^{81565963421049} is an apocalyptic number.

It is an amenable number.

81565963421049 is a deficient number, since it is larger than the sum of its proper divisors (47446867613115).

81565963421049 is a wasteful number, since it uses less digits than its factorization.

81565963421049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59234541366 (or 59234541357 counting only the distinct ones).

The product of its (nonzero) digits is 55987200, while the sum is 63.

The spelling of 81565963421049 in words is "eighty-one trillion, five hundred sixty-five billion, nine hundred sixty-three million, four hundred twenty-one thousand, forty-nine".