18218503 has 4 divisors (see below), whose sum is σ = 18296928. Its totient is φ = 18140080.

The previous prime is 18218491. The next prime is 18218513. The reversal of 18218503 is 30581281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 30581281 = 3739 ⋅8179.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18218503 is a prime.

It is a super-2 number, since 2×18218503² = 663827703122018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18218513) 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, 38863 + ... + 39328.

It is an arithmetic number, because the mean of its divisors is an integer number (4574232).

Almost surely, 2^18218503 is an apocalyptic number.

18218503 is a deficient number, since it is larger than the sum of its proper divisors (78425).

18218503 is an equidigital number, since it uses as much as digits as its factorization.

18218503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78424.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 18218503 is about 4268.3138356967. The cubic root of 18218503 is about 263.1303213756.

Adding to 18218503 its reverse (30581281), we get a palindrome (48799784).

It can be divided in two parts, 18218 and 503, that added together give a triangular number (18721 = T₁₉₃).

The spelling of 18218503 in words is "eighteen million, two hundred eighteen thousand, five hundred three".