81966918 has 16 divisors (see below), whose sum is σ = 178837056. Its totient is φ = 24838440.

The previous prime is 81966869. The next prime is 81966947.

81966918 is nontrivially palindromic in base 10.

It is a congruent 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, 620896 + ... + 621027.

It is an arithmetic number, because the mean of its divisors is an integer number (11177316).

Almost surely, 2^81966918 is an apocalyptic number.

81966918 is an abundant number, since it is smaller than the sum of its proper divisors (96870138).

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

81966918 is a wasteful number, since it uses less digits than its factorization.

81966918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1241939.

The product of its digits is 186624, while the sum is 48.

The square root of 81966918 is about 9053.5583059922. The cubic root of 81966918 is about 434.3897162725.

The spelling of 81966918 in words is "eighty-one million, nine hundred sixty-six thousand, nine hundred eighteen".