81281688 has 16 divisors (see below), whose sum is σ = 203204280. Its totient is φ = 27093888.

The previous prime is 81281687. The next prime is 81281713. The reversal of 81281688 is 88618218.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81281687) 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, 1693345 + ... + 1693392.

Almost surely, 2^81281688 is an apocalyptic number.

It is an amenable number.

81281688 is an abundant number, since it is smaller than the sum of its proper divisors (121922592).

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

81281688 is a wasteful number, since it uses less digits than its factorization.

81281688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3386746 (or 3386742 counting only the distinct ones).

The product of its digits is 49152, while the sum is 42.

The square root of 81281688 is about 9015.6357512934. The cubic root of 81281688 is about 433.1758517824.

The spelling of 81281688 in words is "eighty-one million, two hundred eighty-one thousand, six hundred eighty-eight".