81111618 has 40 divisors (see below), whose sum is σ = 207717312. Its totient is φ = 23174424.

The previous prime is 81111617. The next prime is 81111619. The reversal of 81111618 is 81611118.

It is an interprime number because it is at equal distance from previous prime (81111617) and next prime (81111619).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 81111591 and 81111600.

It is not an unprimeable number, because it can be changed into a prime (81111617) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 34630 + ... + 36897.

Almost surely, 2^81111618 is an apocalyptic number.

81111618 is an abundant number, since it is smaller than the sum of its proper divisors (126605694).

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

81111618 is a wasteful number, since it uses less digits than its factorization.

81111618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71548 (or 71539 counting only the distinct ones).

The product of its digits is 384, while the sum is 27.

The square root of 81111618 is about 9006.1988652261. The cubic root of 81111618 is about 432.8735218640.

Subtracting 81111618 from its reverse (81611118), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 81111618 in words is "eighty-one million, one hundred eleven thousand, six hundred eighteen".