81577 has 6 divisors (see below), whose sum is σ = 85358. Its totient is φ = 77952.

The previous prime is 81569. The next prime is 81611. The reversal of 81577 is 77518.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 11881 + 69696 = 109^2 + 264^2 .

It is not a de Polignac number, because 81577 - 2³ = 81569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81517) 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, 793 + ... + 889.

2⁸¹⁵⁷⁷ is an apocalyptic number.

It is an amenable number.

81577 is a deficient number, since it is larger than the sum of its proper divisors (3781).

81577 is an equidigital number, since it uses as much as digits as its factorization.

81577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155 (or 126 counting only the distinct ones).

The product of its digits is 1960, while the sum is 28.

The square root of 81577 is about 285.6168762521. The cubic root of 81577 is about 43.3699821451.

The spelling of 81577 in words is "eighty-one thousand, five hundred seventy-seven".