81575280 has 120 divisors (see below), whose sum is σ = 276290352. Its totient is φ = 21568512.

The previous prime is 81575261. The next prime is 81575287. The reversal of 81575280 is 8257518.

81575280 is a `hidden beast` number, since 8 + 1 + 575 + 2 + 80 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81575287) 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, 98227 + ... + 99053.

Almost surely, 2^81575280 is an apocalyptic number.

81575280 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 81575280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (138145176).

81575280 is an abundant number, since it is smaller than the sum of its proper divisors (194715072).

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

81575280 is a wasteful number, since it uses less digits than its factorization.

81575280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 983 (or 974 counting only the distinct ones).

The product of its (nonzero) digits is 22400, while the sum is 36.

The square root of 81575280 is about 9031.9034538684. The cubic root of 81575280 is about 433.6967733329.

The spelling of 81575280 in words is "eighty-one million, five hundred seventy-five thousand, two hundred eighty".