81090880 has 112 divisors (see below), whose sum is σ = 211098384. Its totient is φ = 29491200.

The previous prime is 81090871. The next prime is 81090929. The reversal of 81090880 is 8809018.

It can be written as a sum of positive squares in 8 ways, for example, as 952576 + 80138304 = 976^2 + 8952^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 420064 + ... + 420256.

It is an arithmetic number, because the mean of its divisors is an integer number (1884807).

Almost surely, 2^81090880 is an apocalyptic number.

81090880 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81090880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105549192).

81090880 is an abundant number, since it is smaller than the sum of its proper divisors (130007504).

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

81090880 is a wasteful number, since it uses less digits than its factorization.

81090880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324 (or 314 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 34.

The square root of 81090880 is about 9005.0474735006. The cubic root of 81090880 is about 432.8366274524.

Adding to 81090880 its reverse (8809018), we get a palindrome (89899898).

The spelling of 81090880 in words is "eighty-one million, ninety thousand, eight hundred eighty".