81186988 has 12 divisors (see below), whose sum is σ = 143162712. Its totient is φ = 40283360.

The previous prime is 81186983. The next prime is 81187013. The reversal of 81186988 is 88968118.

It is not an unprimeable number, because it can be changed into a prime (81186983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76945 + ... + 77992.

It is an arithmetic number, because the mean of its divisors is an integer number (11930226).

Almost surely, 2^81186988 is an apocalyptic number.

It is an amenable number.

81186988 is a deficient number, since it is larger than the sum of its proper divisors (61975724).

81186988 is a wasteful number, since it uses less digits than its factorization.

81186988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155072 (or 155070 counting only the distinct ones).

The product of its digits is 221184, while the sum is 49.

The square root of 81186988 is about 9010.3822338456. The cubic root of 81186988 is about 433.0075576448.

The spelling of 81186988 in words is "eighty-one million, one hundred eighty-six thousand, nine hundred eighty-eight".