81328590 has 128 divisors (see below), whose sum is σ = 254776320. Its totient is φ = 18071424.

The previous prime is 81328589. The next prime is 81328591. The reversal of 81328590 is 9582318.

It is an interprime number because it is at equal distance from previous prime (81328589) and next prime (81328591).

It is a super-2 number, since 2×81328590² = 13228679102776200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81328591) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 69349 + ... + 70511.

It is an arithmetic number, because the mean of its divisors is an integer number (1990440).

Almost surely, 2^81328590 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81328590, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127388160).

81328590 is an abundant number, since it is smaller than the sum of its proper divisors (173447730).

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

81328590 is a wasteful number, since it uses less digits than its factorization.

81328590 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1223 (or 1217 counting only the distinct ones).

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

The square root of 81328590 is about 9018.2365238443. The cubic root of 81328590 is about 433.2591542980.

It can be divided in two parts, 81328 and 590, that added together give a palindrome (81918).

The spelling of 81328590 in words is "eighty-one million, three hundred twenty-eight thousand, five hundred ninety".