81166140 has 72 divisors (see below), whose sum is σ = 268592688. Its totient is φ = 19676160.

The previous prime is 81166139. The next prime is 81166147. The reversal of 81166140 is 4166118.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81166147) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18517 + ... + 22476.

It is an arithmetic number, because the mean of its divisors is an integer number (3730454).

Almost surely, 2^81166140 is an apocalyptic number.

It is an amenable number.

81166140 is an abundant number, since it is smaller than the sum of its proper divisors (187426548).

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

81166140 is a wasteful number, since it uses less digits than its factorization.

81166140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41019 (or 41014 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 81166140 is about 9009.2252719088. The cubic root of 81166140 is about 432.9704904800.

The spelling of 81166140 in words is "eighty-one million, one hundred sixty-six thousand, one hundred forty".