81845072 has 40 divisors (see below), whose sum is σ = 168739200. Its totient is φ = 38323712.

The previous prime is 81845069. The next prime is 81845081. The reversal of 81845072 is 27054818.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64379 + ... + 65637.

It is an arithmetic number, because the mean of its divisors is an integer number (4218480).

Almost surely, 2^81845072 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 81845072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (84369600).

81845072 is an abundant number, since it is smaller than the sum of its proper divisors (86894128).

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

81845072 is a wasteful number, since it uses less digits than its factorization.

81845072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1523 (or 1517 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 81845072 is about 9046.8266259501. The cubic root of 81845072 is about 434.1743655799.

The spelling of 81845072 in words is "eighty-one million, eight hundred forty-five thousand, seventy-two".