81929808 has 60 divisors (see below), whose sum is σ = 234899028. Its totient is φ = 26641920.

The previous prime is 81929777. The next prime is 81929821. The reversal of 81929808 is 80892918.

It can be written as a sum of positive squares in 2 ways, for example, as 4981824 + 76947984 = 2232^2 + 8772^2 .

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1035 + ... + 12842.

Almost surely, 2^81929808 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 81929808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117449514).

81929808 is an abundant number, since it is smaller than the sum of its proper divisors (152969220).

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

81929808 is a wasteful number, since it uses less digits than its factorization.

81929808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13932 (or 13923 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 45.

The square root of 81929808 is about 9051.5086035423. The cubic root of 81929808 is about 434.3241506510.

The spelling of 81929808 in words is "eighty-one million, nine hundred twenty-nine thousand, eight hundred eight".