81655618 has 16 divisors (see below), whose sum is σ = 133766784. Its totient is φ = 37074960.

The previous prime is 81655601. The next prime is 81655661.

81655618 is nontrivially palindromic in base 10.

It is a super-3 number, since 3×81655618³ (a number of 25 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27796 + ... + 30592.

It is an arithmetic number, because the mean of its divisors is an integer number (8360424).

Almost surely, 2^81655618 is an apocalyptic number.

81655618 is a deficient number, since it is larger than the sum of its proper divisors (52111166).

81655618 is a wasteful number, since it uses less digits than its factorization.

81655618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4137.

The product of its digits is 57600, while the sum is 40.

The square root of 81655618 is about 9036.3498161592. The cubic root of 81655618 is about 433.8390995362.

The spelling of 81655618 in words is "eighty-one million, six hundred fifty-five thousand, six hundred eighteen".