81442165 has 12 divisors (see below), whose sum is σ = 113686956. Its totient is φ = 55845888.

The previous prime is 81442159. The next prime is 81442181. The reversal of 81442165 is 56124418.

It can be written as a sum of positive squares in 2 ways, for example, as 39425841 + 42016324 = 6279^2 + 6482^2 .

It is not a de Polignac number, because 81442165 - 2³ = 81442157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 165964 + ... + 166453.

It is an arithmetic number, because the mean of its divisors is an integer number (9473913).

Almost surely, 2^81442165 is an apocalyptic number.

It is an amenable number.

81442165 is a deficient number, since it is larger than the sum of its proper divisors (32244791).

81442165 is a wasteful number, since it uses less digits than its factorization.

81442165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332436 (or 332429 counting only the distinct ones).

The product of its digits is 7680, while the sum is 31.

The square root of 81442165 is about 9024.5312897679. The cubic root of 81442165 is about 433.4607419571.

The spelling of 81442165 in words is "eighty-one million, four hundred forty-two thousand, one hundred sixty-five".