81650825081 has 6 divisors (see below), whose sum is σ = 94981572090. Its totient is φ = 69986421456.

The previous prime is 81650825063. The next prime is 81650825083. The reversal of 81650825081 is 18052805618.

It can be written as a sum of positive squares in only one way, i.e., 79995637225 + 1655187856 = 282835^2 + 40684^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81650825081 is a prime.

It is a super-2 number, since 2×81650825081² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81650825083) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 833171636 + ... + 833171733.

It is an arithmetic number, because the mean of its divisors is an integer number (15830262015).

Almost surely, 2^81650825081 is an apocalyptic number.

It is an amenable number.

81650825081 is a deficient number, since it is larger than the sum of its proper divisors (13330747009).

81650825081 is a wasteful number, since it uses less digits than its factorization.

81650825081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1666343383 (or 1666343376 counting only the distinct ones).

The product of its (nonzero) digits is 153600, while the sum is 44.

The spelling of 81650825081 in words is "eighty-one billion, six hundred fifty million, eight hundred twenty-five thousand, eighty-one".