81611618 has 16 divisors (see below), whose sum is σ = 133685856. Its totient is φ = 37057440.

The previous prime is 81611531. The next prime is 81611639.

81611618 is nontrivially palindromic in base 10.

It is a Curzon number.

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, 36830 + ... + 38982.

It is an arithmetic number, because the mean of its divisors is an integer number (8355366).

Almost surely, 2^81611618 is an apocalyptic number.

81611618 is a deficient number, since it is larger than the sum of its proper divisors (52074238).

81611618 is a wasteful number, since it uses less digits than its factorization.

81611618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3889.

The product of its digits is 2304, while the sum is 32.

The square root of 81611618 is about 9033.9148767298. The cubic root of 81611618 is about 433.7611610324.

It can be divided in two parts, 8161 and 1618, that added together give a palindrome (9779).

The spelling of 81611618 in words is "eighty-one million, six hundred eleven thousand, six hundred eighteen".