81188380 has 96 divisors (see below), whose sum is σ = 216760320. Its totient is φ = 24848640.

The previous prime is 81188351. The next prime is 81188383. The reversal of 81188380 is 8388118.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81188383) 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, 55701 + ... + 57139.

It is an arithmetic number, because the mean of its divisors is an integer number (2257920).

Almost surely, 2^81188380 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 81188380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108380160).

81188380 is an abundant number, since it is smaller than the sum of its proper divisors (135571940).

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

81188380 is a wasteful number, since it uses less digits than its factorization.

81188380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1499 (or 1497 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 37.

The square root of 81188380 is about 9010.4594777403. The cubic root of 81188380 is about 433.0100323561.

The spelling of 81188380 in words is "eighty-one million, one hundred eighty-eight thousand, three hundred eighty".