81190980 has 216 divisors, whose sum is σ = 284166792. Its totient is φ = 18690048.

The previous prime is 81190969. The next prime is 81191003. The reversal of 81190980 is 8909118.

It can be written as a sum of positive squares in 12 ways, for example, as 42850116 + 38340864 = 6546^2 + 6192^2 .

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

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 71 ways as a sum of consecutive naturals, for example, 517062 + ... + 517218.

It is an arithmetic number, because the mean of its divisors is an integer number (1315587).

Almost surely, 2^81190980 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 81190980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142083396).

81190980 is an abundant number, since it is smaller than the sum of its proper divisors (202975812).

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

81190980 is a wasteful number, since it uses less digits than its factorization.

81190980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215 (or 197 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 36.

The square root of 81190980 is about 9010.6037533564. The cubic root of 81190980 is about 433.0146545860.

The spelling of 81190980 in words is "eighty-one million, one hundred ninety thousand, nine hundred eighty".