81618 has 16 divisors (see below), whose sum is σ = 166656. Its totient is φ = 26640.

The previous prime is 81611. The next prime is 81619.

81618 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×81618² = 13322995848, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

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

81618 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 255 + ... + 477.

It is an arithmetic number, because the mean of its divisors is an integer number (10416).

2⁸¹⁶¹⁸ is an apocalyptic number.

81618 is an abundant number, since it is smaller than the sum of its proper divisors (85038).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83328).

81618 is a wasteful number, since it uses less digits than its factorization.

81618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 289.

The product of its digits is 384, while the sum is 24.

The square root of 81618 is about 285.6886417063. The cubic root of 81618 is about 43.3772467395.

The spelling of 81618 in words is "eighty-one thousand, six hundred eighteen".