81688956 has 24 divisors (see below), whose sum is σ = 190794240. Its totient is φ = 27202992.

The previous prime is 81688909. The next prime is 81689033. The reversal of 81688956 is 65988618.

It is a junction number, because it is equal to n+sod(n) for n = 81688899 and 81688908.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 12405 + ... + 17811.

It is an arithmetic number, because the mean of its divisors is an integer number (7949760).

Almost surely, 2^81688956 is an apocalyptic number.

It is an amenable number.

81688956 is an abundant number, since it is smaller than the sum of its proper divisors (109105284).

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

81688956 is a wasteful number, since it uses less digits than its factorization.

81688956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6673 (or 6671 counting only the distinct ones).

The product of its digits is 829440, while the sum is 51.

The square root of 81688956 is about 9038.1942886840. The cubic root of 81688956 is about 433.8981334821.

The spelling of 81688956 in words is "eighty-one million, six hundred eighty-eight thousand, nine hundred fifty-six".