81981360 has 120 divisors (see below), whose sum is σ = 284279424. Its totient is φ = 21150720.

The previous prime is 81981343. The next prime is 81981379. The reversal of 81981360 is 6318918.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20484 + ... + 24156.

Almost surely, 2^81981360 is an apocalyptic number.

81981360 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 81981360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142139712).

81981360 is an abundant number, since it is smaller than the sum of its proper divisors (202298064).

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

81981360 is a wasteful number, since it uses less digits than its factorization.

81981360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3723 (or 3714 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 81981360 is about 9054.3558578178. The cubic root of 81981360 is about 434.4152269217.

The spelling of 81981360 in words is "eighty-one million, nine hundred eighty-one thousand, three hundred sixty".