81390528 has 224 divisors, whose sum is σ = 262534400. Its totient is φ = 24634368.

The previous prime is 81390521. The next prime is 81390541. The reversal of 81390528 is 82509318.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81390492 and 81390501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81390521) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1214751 + ... + 1214817.

Almost surely, 2^81390528 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 81390528, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131267200).

81390528 is an abundant number, since it is smaller than the sum of its proper divisors (181143872).

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

81390528 is a wasteful number, since it uses less digits than its factorization.

81390528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144 (or 128 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 81390528 is about 9021.6699119398. The cubic root of 81390528 is about 433.3691131534.

It can be divided in two parts, 81390 and 528, that added together give a palindrome (81918).

The spelling of 81390528 in words is "eighty-one million, three hundred ninety thousand, five hundred twenty-eight".