81644808 has 64 divisors (see below), whose sum is σ = 234178560. Its totient is φ = 23236416.

The previous prime is 81644789. The next prime is 81644839. The reversal of 81644808 is 80844618.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50785 + ... + 52367.

It is an arithmetic number, because the mean of its divisors is an integer number (3659040).

Almost surely, 2^81644808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81644808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117089280).

81644808 is an abundant number, since it is smaller than the sum of its proper divisors (152533752).

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

81644808 is a wasteful number, since it uses less digits than its factorization.

81644808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1906 (or 1902 counting only the distinct ones).

The product of its (nonzero) digits is 49152, while the sum is 39.

The square root of 81644808 is about 9035.7516566139. The cubic root of 81644808 is about 433.8199540577.

The spelling of 81644808 in words is "eighty-one million, six hundred forty-four thousand, eight hundred eight".