81697888 has 24 divisors (see below), whose sum is σ = 162078840. Its totient is φ = 40535040.

The previous prime is 81697883. The next prime is 81697897. The reversal of 81697888 is 88879618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81697883) 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, 5553 + ... + 13936.

It is an arithmetic number, because the mean of its divisors is an integer number (6753285).

Almost surely, 2^81697888 is an apocalyptic number.

It is an amenable number.

81697888 is a deficient number, since it is larger than the sum of its proper divisors (80380952).

81697888 is a wasteful number, since it uses less digits than its factorization.

81697888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19630 (or 19622 counting only the distinct ones).

The product of its digits is 1548288, while the sum is 55.

The square root of 81697888 is about 9038.6884004262. The cubic root of 81697888 is about 433.9139472758.

The spelling of 81697888 in words is "eighty-one million, six hundred ninety-seven thousand, eight hundred eighty-eight".