81813808 has 40 divisors (see below), whose sum is σ = 164373408. Its totient is φ = 39416832.

The previous prime is 81813803. The next prime is 81813833. The reversal of 81813808 is 80831818.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (81813803) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66285 + ... + 67507.

Almost surely, 2^81813808 is an apocalyptic number.

It is an amenable number.

81813808 is an abundant number, since it is smaller than the sum of its proper divisors (82559600).

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

81813808 is a wasteful number, since it uses less digits than its factorization.

81813808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1381 (or 1375 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 37.

The square root of 81813808 is about 9045.0985622048. The cubic root of 81813808 is about 434.1190751156.

It can be divided in two parts, 81813 and 808, that added together give a triangular number (82621 = T₄₀₆).

The spelling of 81813808 in words is "eighty-one million, eight hundred thirteen thousand, eight hundred eight".