81570960 has 120 divisors (see below), whose sum is σ = 275603640. Its totient is φ = 21620736.

The previous prime is 81570911. The next prime is 81570961. The reversal of 81570960 is 6907518.

81570960 is a `hidden beast` number, since 81 + 570 + 9 + 6 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 11614464 + 69956496 = 3408^2 + 8364^2 .

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 not an unprimeable number, because it can be changed into a prime (81570961) 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, 199236 + ... + 199644.

It is an arithmetic number, because the mean of its divisors is an integer number (2296697).

Almost surely, 2^81570960 is an apocalyptic number.

81570960 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 81570960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137801820).

81570960 is an abundant number, since it is smaller than the sum of its proper divisors (194032680).

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

81570960 is a wasteful number, since it uses less digits than its factorization.

81570960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 705 (or 696 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 36.

The square root of 81570960 is about 9031.6642984557. The cubic root of 81570960 is about 433.6891174060.

The spelling of 81570960 in words is "eighty-one million, five hundred seventy thousand, nine hundred sixty".