18138257 has 4 divisors (see below), whose sum is σ = 18151140. Its totient is φ = 18125376.

The previous prime is 18138247. The next prime is 18138343. The reversal of 18138257 is 75283181.

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 12397441 + 5740816 = 3521^2 + 2396^2 .

It is a cyclic number.

It is not a de Polignac number, because 18138257 - 2¹⁰ = 18137233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18138227) 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, 4028 + ... + 7245.

It is an arithmetic number, because the mean of its divisors is an integer number (4537785).

Almost surely, 2^18138257 is an apocalyptic number.

It is an amenable number.

18138257 is a deficient number, since it is larger than the sum of its proper divisors (12883).

18138257 is a wasteful number, since it uses less digits than its factorization.

18138257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12882.

The product of its digits is 13440, while the sum is 35.

The square root of 18138257 is about 4258.9032625783. The cubic root of 18138257 is about 262.7434210646.

The spelling of 18138257 in words is "eighteen million, one hundred thirty-eight thousand, two hundred fifty-seven".