81155328 has 72 divisors (see below), whose sum is σ = 217367136. Its totient is φ = 26880000.

The previous prime is 81155317. The next prime is 81155353. The reversal of 81155328 is 82355118.

It is a happy number.

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, 192558 + ... + 192978.

It is an arithmetic number, because the mean of its divisors is an integer number (3018988).

Almost surely, 2^81155328 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 81155328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108683568).

81155328 is an abundant number, since it is smaller than the sum of its proper divisors (136211808).

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

81155328 is a wasteful number, since it uses less digits than its factorization.

81155328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691 (or 677 counting only the distinct ones).

The product of its digits is 9600, while the sum is 33.

The square root of 81155328 is about 9008.6252003288. The cubic root of 81155328 is about 432.9512645449.

The spelling of 81155328 in words is "eighty-one million, one hundred fifty-five thousand, three hundred twenty-eight".