81582072 has 96 divisors (see below), whose sum is σ = 241538640. Its totient is φ = 22809600.

The previous prime is 81582047. The next prime is 81582079. The reversal of 81582072 is 27028518.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81582079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36672 + ... + 38832.

Almost surely, 2^81582072 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 81582072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120769320).

81582072 is an abundant number, since it is smaller than the sum of its proper divisors (159956568).

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

81582072 is a wasteful number, since it uses less digits than its factorization.

81582072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2205 (or 2190 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 33.

The square root of 81582072 is about 9032.2794465185. The cubic root of 81582072 is about 433.7088096047.

The spelling of 81582072 in words is "eighty-one million, five hundred eighty-two thousand, seventy-two".