81688699 has 8 divisors (see below), whose sum is σ = 83856240. Its totient is φ = 79548000.

The previous prime is 81688669. The next prime is 81688721. The reversal of 81688699 is 99688618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81688699 - 2¹¹ = 81686651 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81688609) by changing a digit.

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, 469 + ... + 12790.

It is an arithmetic number, because the mean of its divisors is an integer number (10482030).

Almost surely, 2^81688699 is an apocalyptic number.

81688699 is a deficient number, since it is larger than the sum of its proper divisors (2167541).

81688699 is a wasteful number, since it uses less digits than its factorization.

81688699 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13421.

The product of its digits is 1492992, while the sum is 55.

The square root of 81688699 is about 9038.1800712312. The cubic root of 81688699 is about 433.8976784556.

The spelling of 81688699 in words is "eighty-one million, six hundred eighty-eight thousand, six hundred ninety-nine".