81915169 has 16 divisors (see below), whose sum is σ = 97729920. Its totient is φ = 67173120.

The previous prime is 81915149. The next prime is 81915173. The reversal of 81915169 is 96151918.

It is not a de Polignac number, because 81915169 - 2²¹ = 79818017 is a prime.

It is a super-2 number, since 2×81915169² = 13420189824597122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81915109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21154 + ... + 24724.

It is an arithmetic number, because the mean of its divisors is an integer number (6108120).

Almost surely, 2^81915169 is an apocalyptic number.

It is an amenable number.

81915169 is a deficient number, since it is larger than the sum of its proper divisors (15814751).

81915169 is a wasteful number, since it uses less digits than its factorization.

81915169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3720.

The product of its digits is 19440, while the sum is 40.

The square root of 81915169 is about 9050.6999176859. The cubic root of 81915169 is about 434.2982811491.

The spelling of 81915169 in words is "eighty-one million, nine hundred fifteen thousand, one hundred sixty-nine".