81505008 has 160 divisors (see below), whose sum is σ = 263316480. Its totient is φ = 23950080.

The previous prime is 81504961. The next prime is 81505009. The reversal of 81505008 is 80050518.

81505008 is a `hidden beast` number, since 8 + 150 + 500 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81505009) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 128853 + ... + 129483.

It is an arithmetic number, because the mean of its divisors is an integer number (1645728).

Almost surely, 2^81505008 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 81505008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131658240).

81505008 is an abundant number, since it is smaller than the sum of its proper divisors (181811472).

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

81505008 is a wasteful number, since it uses less digits than its factorization.

81505008 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 684 (or 672 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 27.

The square root of 81505008 is about 9028.0124058399. The cubic root of 81505008 is about 433.5722033442.

The spelling of 81505008 in words is "eighty-one million, five hundred five thousand, eight".