81866012 has 12 divisors (see below), whose sum is σ = 146760096. Its totient is φ = 39934560.

The previous prime is 81865991. The next prime is 81866017. The reversal of 81866012 is 21066818.

It is a self number, because there is not a number n which added to its sum of digits gives 81866012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81866017) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 249428 + ... + 249755.

It is an arithmetic number, because the mean of its divisors is an integer number (12230008).

Almost surely, 2^81866012 is an apocalyptic number.

81866012 is a gapful number since it is divisible by the number (82) formed by its first and last digit.

It is an amenable number.

81866012 is a deficient number, since it is larger than the sum of its proper divisors (64894084).

81866012 is a wasteful number, since it uses less digits than its factorization.

81866012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499228 (or 499226 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 81866012 is about 9047.9838638229. The cubic root of 81866012 is about 434.2113901507.

The spelling of 81866012 in words is "eighty-one million, eight hundred sixty-six thousand, twelve".