18138529 has 4 divisors (see below), whose sum is σ = 18387076. Its totient is φ = 17889984.

The previous prime is 18138517. The next prime is 18138539. The reversal of 18138529 is 92583181.

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 9000000 + 9138529 = 3000^2 + 3023^2 .

It is a cyclic number.

It is not a de Polignac number, because 18138529 - 2⁹ = 18138017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18138509) 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, 124164 + ... + 124309.

It is an arithmetic number, because the mean of its divisors is an integer number (4596769).

Almost surely, 2^18138529 is an apocalyptic number.

It is an amenable number.

18138529 is a deficient number, since it is larger than the sum of its proper divisors (248547).

18138529 is an equidigital number, since it uses as much as digits as its factorization.

18138529 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248546.

The product of its digits is 17280, while the sum is 37.

The square root of 18138529 is about 4258.9351955624. The cubic root of 18138529 is about 262.7447344185.

The spelling of 18138529 in words is "eighteen million, one hundred thirty-eight thousand, five hundred twenty-nine".