81580772 has 48 divisors (see below), whose sum is σ = 177999360. Its totient is φ = 31853952.

The previous prime is 81580769. The next prime is 81580777. The reversal of 81580772 is 27708518.

It is not an unprimeable number, because it can be changed into a prime (81580777) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27338 + ... + 30174.

It is an arithmetic number, because the mean of its divisors is an integer number (3708320).

Almost surely, 2^81580772 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 81580772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88999680).

81580772 is an abundant number, since it is smaller than the sum of its proper divisors (96418588).

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

81580772 is a wasteful number, since it uses less digits than its factorization.

81580772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2940 (or 2938 counting only the distinct ones).

The product of its (nonzero) digits is 31360, while the sum is 38.

The square root of 81580772 is about 9032.2074821164. The cubic root of 81580772 is about 433.7065058941.

The spelling of 81580772 in words is "eighty-one million, five hundred eighty thousand, seven hundred seventy-two".