81809808 has 20 divisors (see below), whose sum is σ = 211342128. Its totient is φ = 27269920.

The previous prime is 81809789. The next prime is 81809809. The reversal of 81809808 is 80890818.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 81809808.

It is not an unprimeable number, because it can be changed into a prime (81809809) 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, 852138 + ... + 852233.

Almost surely, 2^81809808 is an apocalyptic number.

It is an amenable number.

81809808 is an abundant number, since it is smaller than the sum of its proper divisors (129532320).

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

81809808 is a wasteful number, since it uses less digits than its factorization.

81809808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1704382 (or 1704376 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 42.

The square root of 81809808 is about 9044.8774452725. The cubic root of 81809808 is about 434.1120000890.

The spelling of 81809808 in words is "eighty-one million, eight hundred nine thousand, eight hundred eight".