18117481 has 4 divisors (see below), whose sum is σ = 18296964. Its totient is φ = 17938000.

The previous prime is 18117443. The next prime is 18117497. The reversal of 18117481 is 18471181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15840400 + 2277081 = 3980^2 + 1509^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18117481 is a prime.

It is a super-2 number, since 2×18117481² = 656486235570722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18117401) 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, 89590 + ... + 89791.

It is an arithmetic number, because the mean of its divisors is an integer number (4574241).

Almost surely, 2^18117481 is an apocalyptic number.

It is an amenable number.

18117481 is a deficient number, since it is larger than the sum of its proper divisors (179483).

18117481 is a wasteful number, since it uses less digits than its factorization.

18117481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179482.

The product of its digits is 1792, while the sum is 31.

The square root of 18117481 is about 4256.4634381139. The cubic root of 18117481 is about 262.6430651733.

The spelling of 18117481 in words is "eighteen million, one hundred seventeen thousand, four hundred eighty-one".