81686608 has 20 divisors (see below), whose sum is σ = 160177248. Its totient is φ = 40350560.

The previous prime is 81686597. The next prime is 81686609. The reversal of 81686608 is 80668618.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81686609) 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, 29428 + ... + 32083.

Almost surely, 2^81686608 is an apocalyptic number.

It is an amenable number.

81686608 is a deficient number, since it is larger than the sum of its proper divisors (78490640).

81686608 is a wasteful number, since it uses less digits than its factorization.

81686608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61602 (or 61596 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 43.

The square root of 81686608 is about 9038.0643945482. The cubic root of 81686608 is about 433.8939762389.

The spelling of 81686608 in words is "eighty-one million, six hundred eighty-six thousand, six hundred eight".