181118521 has 4 divisors (see below), whose sum is σ = 182440692. Its totient is φ = 179796352.

The previous prime is 181118519. The next prime is 181118549. The reversal of 181118521 is 125811181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125811181 = 433 ⋅290557.

It can be written as a sum of positive squares in 2 ways, for example, as 92852496 + 88266025 = 9636^2 + 9395^2 .

It is a cyclic number.

It is not a de Polignac number, because 181118521 - 2¹ = 181118519 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 181118521.

It is not an unprimeable number, because it can be changed into a prime (181118921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 660880 + ... + 661153.

It is an arithmetic number, because the mean of its divisors is an integer number (45610173).

Almost surely, 2^181118521 is an apocalyptic number.

It is an amenable number.

181118521 is a deficient number, since it is larger than the sum of its proper divisors (1322171).

181118521 is a wasteful number, since it uses less digits than its factorization.

181118521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1322170.

The product of its digits is 640, while the sum is 28.

The square root of 181118521 is about 13458.0281245062. The cubic root of 181118521 is about 565.7887238101.

The spelling of 181118521 in words is "one hundred eighty-one million, one hundred eighteen thousand, five hundred twenty-one".