181981440 has 108 divisors (see below), whose sum is σ = 629676684. Its totient is φ = 48525312.

The previous prime is 181981433. The next prime is 181981453. The reversal of 181981440 is 44189181.

It can be written as a sum of positive squares in 2 ways, for example, as 99680256 + 82301184 = 9984^2 + 9072^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 181981395 and 181981404.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3622 + ... + 19418.

Almost surely, 2^181981440 is an apocalyptic number.

181981440 is a gapful number since it is divisible by the number (10) 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 181981440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (314838342).

181981440 is an abundant number, since it is smaller than the sum of its proper divisors (447695244).

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

181981440 is a wasteful number, since it uses less digits than its factorization.

181981440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15824 (or 15807 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The square root of 181981440 is about 13490.0496663281. The cubic root of 181981440 is about 566.6858463328.

The spelling of 181981440 in words is "one hundred eighty-one million, nine hundred eighty-one thousand, four hundred forty".