81242188 has 12 divisors (see below), whose sum is σ = 142393552. Its totient is φ = 40558320.

The previous prime is 81242159. The next prime is 81242237. The reversal of 81242188 is 88124218.

It is a super-2 number, since 2×81242188² = 13200586222054688, which contains 22 as substring.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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, 12720 + ... + 18007.

Almost surely, 2^81242188 is an apocalyptic number.

It is an amenable number.

81242188 is a deficient number, since it is larger than the sum of its proper divisors (61151364).

81242188 is a wasteful number, since it uses less digits than its factorization.

81242188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31392 (or 31390 counting only the distinct ones).

The product of its digits is 8192, while the sum is 34.

The square root of 81242188 is about 9013.4448464502. Note that the first 3 decimals coincide. The cubic root of 81242188 is about 433.1056710771.

The spelling of 81242188 in words is "eighty-one million, two hundred forty-two thousand, one hundred eighty-eight".