81617 has 4 divisors (see below), whose sum is σ = 86436. Its totient is φ = 76800.

The previous prime is 81611. The next prime is 81619. The reversal of 81617 is 71618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71618 = 2 ⋅35809.

It can be written as a sum of positive squares in 2 ways, for example, as 55696 + 25921 = 236^2 + 161^2 .

It is a cyclic number.

It is not a de Polignac number, because 81617 - 2⁶ = 81553 is a prime.

It is a super-2 number, since 2×81617² = 13322669378, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81592 and 81601.

It is not an unprimeable number, because it can be changed into a prime (81611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2384 + ... + 2417.

It is an arithmetic number, because the mean of its divisors is an integer number (21609).

2⁸¹⁶¹⁷ is an apocalyptic number.

It is an amenable number.

81617 is a deficient number, since it is larger than the sum of its proper divisors (4819).

81617 is a wasteful number, since it uses less digits than its factorization.

81617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4818.

The product of its digits is 336, while the sum is 23.

The square root of 81617 is about 285.6868915439. The cubic root of 81617 is about 43.3770695832.

Subtracting from 81617 its reverse (71618), we obtain a palindrome (9999).

The spelling of 81617 in words is "eighty-one thousand, six hundred seventeen".