81857328 has 40 divisors (see below), whose sum is σ = 241675008. Its totient is φ = 23387712.

The previous prime is 81857323. The next prime is 81857341. The reversal of 81857328 is 82375818.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 81857328.

It is not an unprimeable number, because it can be changed into a prime (81857323) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 121476 + ... + 122147.

Almost surely, 2^81857328 is an apocalyptic number.

It is an amenable number.

81857328 is an abundant number, since it is smaller than the sum of its proper divisors (159817680).

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

81857328 is a wasteful number, since it uses less digits than its factorization.

81857328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243641 (or 243635 counting only the distinct ones).

The product of its digits is 107520, while the sum is 42.

The square root of 81857328 is about 9047.5039651829. The cubic root of 81857328 is about 434.1960365057.

The spelling of 81857328 in words is "eighty-one million, eight hundred fifty-seven thousand, three hundred twenty-eight".