81504800 has 144 divisors (see below), whose sum is σ = 227376072. Its totient is φ = 28262400.

The previous prime is 81504799. The next prime is 81504809. The reversal of 81504800 is 840518.

It can be written as a sum of positive squares in 12 ways, for example, as 1008016 + 80496784 = 1004^2 + 8972^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 81504800.

It is not an unprimeable number, because it can be changed into a prime (81504809) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 176570 + ... + 177030.

Almost surely, 2^81504800 is an apocalyptic number.

81504800 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81504800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113688036).

81504800 is an abundant number, since it is smaller than the sum of its proper divisors (145871272).

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

81504800 is a wasteful number, since it uses less digits than its factorization.

81504800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511 (or 498 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 81504800 is about 9028.0008861320. Note that the first 3 decimals coincide. The cubic root of 81504800 is about 433.5718345198.

The spelling of 81504800 in words is "eighty-one million, five hundred four thousand, eight hundred".