81699816 has 32 divisors (see below), whose sum is σ = 222818400. Its totient is φ = 24757440.

The previous prime is 81699799. The next prime is 81699823. The reversal of 81699816 is 61899618.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 154471 + ... + 154998.

It is an arithmetic number, because the mean of its divisors is an integer number (6963075).

Almost surely, 2^81699816 is an apocalyptic number.

It is an amenable number.

81699816 is an abundant number, since it is smaller than the sum of its proper divisors (141118584).

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

81699816 is a wasteful number, since it uses less digits than its factorization.

81699816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 309489 (or 309485 counting only the distinct ones).

The product of its digits is 186624, while the sum is 48.

The square root of 81699816 is about 9038.7950524392. The cubic root of 81699816 is about 433.9173605811.

The spelling of 81699816 in words is "eighty-one million, six hundred ninety-nine thousand, eight hundred sixteen".