81508608 has 108 divisors (see below), whose sum is σ = 248953068. Its totient is φ = 25559040.

The previous prime is 81508597. The next prime is 81508621. The reversal of 81508608 is 80680518.

It can be written as a sum of positive squares in 2 ways, for example, as 47775744 + 33732864 = 6912^2 + 5808^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 38128 + ... + 40208.

It is an arithmetic number, because the mean of its divisors is an integer number (2305121).

Almost surely, 2^81508608 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 81508608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124476534).

81508608 is an abundant number, since it is smaller than the sum of its proper divisors (167444460).

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

81508608 is a wasteful number, since it uses less digits than its factorization.

81508608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2120 (or 2103 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 36.

The square root of 81508608 is about 9028.2117830720. The cubic root of 81508608 is about 433.5785867432.

The spelling of 81508608 in words is "eighty-one million, five hundred eight thousand, six hundred eight".