81881166 has 16 divisors (see below), whose sum is σ = 164145744. Its totient is φ = 27229824.

The previous prime is 81881153. The next prime is 81881167. The reversal of 81881166 is 66118818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81881167) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13161 + ... + 18356.

It is an arithmetic number, because the mean of its divisors is an integer number (10259109).

Almost surely, 2^81881166 is an apocalyptic number.

81881166 is an abundant number, since it is smaller than the sum of its proper divisors (82264578).

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

81881166 is a wasteful number, since it uses less digits than its factorization.

81881166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31955.

The product of its digits is 18432, while the sum is 39.

The square root of 81881166 is about 9048.8212492015. The cubic root of 81881166 is about 434.2381804033.

The spelling of 81881166 in words is "eighty-one million, eight hundred eighty-one thousand, one hundred sixty-six".