18218549 has 4 divisors (see below), whose sum is σ = 19177440. Its totient is φ = 17259660.

The previous prime is 18218527. The next prime is 18218561. The reversal of 18218549 is 94581281.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18218549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18218449) 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, 479417 + ... + 479454.

It is an arithmetic number, because the mean of its divisors is an integer number (4794360).

Almost surely, 2^18218549 is an apocalyptic number.

18218549 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

18218549 is a deficient number, since it is larger than the sum of its proper divisors (958891).

18218549 is an equidigital number, since it uses as much as digits as its factorization.

18218549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 958890.

The product of its digits is 23040, while the sum is 38.

The square root of 18218549 is about 4268.3192242380. The cubic root of 18218549 is about 263.1305428351.

The spelling of 18218549 in words is "eighteen million, two hundred eighteen thousand, five hundred forty-nine".