181520 has 20 divisors (see below), whose sum is σ = 422220. Its totient is φ = 72576.

The previous prime is 181513. The next prime is 181523. The reversal of 181520 is 25181.

It can be written as a sum of positive squares in 2 ways, for example, as 30976 + 150544 = 176^2 + 388^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 181520.

It is not an unprimeable number, because it can be changed into a prime (181523) by changing a digit.

181520 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1055 + ... + 1214.

It is an arithmetic number, because the mean of its divisors is an integer number (21111).

2¹⁸¹⁵²⁰ is an apocalyptic number.

181520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

181520 is an abundant number, since it is smaller than the sum of its proper divisors (240700).

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

181520 is a wasteful number, since it uses less digits than its factorization.

181520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2282 (or 2276 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 17.

The square root of 181520 is about 426.0516400626. The cubic root of 181520 is about 56.6206469892.

Subtracting from 181520 its sum of digits (17), we obtain a triangular number (181503 = T₆₀₂).

The spelling of 181520 in words is "one hundred eighty-one thousand, five hundred twenty".