81601 has 4 divisors (see below), whose sum is σ = 87892. Its totient is φ = 75312.

The previous prime is 81569. The next prime is 81611. The reversal of 81601 is 10618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10618 = 2 ⋅5309.

It can be written as a sum of positive squares in 2 ways, for example, as 50625 + 30976 = 225^2 + 176^2 .

It is a cyclic number.

It is not a de Polignac number, because 81601 - 2⁵ = 81569 is a prime.

It is a Duffinian number.

81601 is a lucky number.

It is a congruent number.

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, 3126 + ... + 3151.

It is an arithmetic number, because the mean of its divisors is an integer number (21973).

2⁸¹⁶⁰¹ is an apocalyptic number.

It is an amenable number.

81601 is a deficient number, since it is larger than the sum of its proper divisors (6291).

81601 is a wasteful number, since it uses less digits than its factorization.

81601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6290.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 81601 is about 285.6588874865. The cubic root of 81601 is about 43.3742348859.

The spelling of 81601 in words is "eighty-one thousand, six hundred one".