81616161585 has 32 divisors (see below), whose sum is σ = 153274528512. Its totient is φ = 36301858560.

The previous prime is 81616161563. The next prime is 81616161593. The reversal of 81616161585 is 58516161618.

It is not a de Polignac number, because 81616161585 - 2⁵ = 81616161553 is a prime.

It is a super-2 number, since 2×81616161585² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10500126 + ... + 10507895.

It is an arithmetic number, because the mean of its divisors is an integer number (4789829016).

Almost surely, 2^81616161585 is an apocalyptic number.

It is an amenable number.

81616161585 is a deficient number, since it is larger than the sum of its proper divisors (71658366927).

81616161585 is a wasteful number, since it uses less digits than its factorization.

81616161585 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21008073.

The product of its digits is 345600, while the sum is 48.

The spelling of 81616161585 in words is "eighty-one billion, six hundred sixteen million, one hundred sixty-one thousand, five hundred eighty-five".