18218951 has 4 divisors (see below), whose sum is σ = 19290672. Its totient is φ = 17147232.

The previous prime is 18218947. The next prime is 18218953. The reversal of 18218951 is 15981281.

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

It is a cyclic number.

It is not a de Polignac number, because 18218951 - 2² = 18218947 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 (18218953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 535835 + ... + 535868.

It is an arithmetic number, because the mean of its divisors is an integer number (4822668).

Almost surely, 2^18218951 is an apocalyptic number.

18218951 is a deficient number, since it is larger than the sum of its proper divisors (1071721).

18218951 is a wasteful number, since it uses less digits than its factorization.

18218951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1071720.

The product of its digits is 5760, while the sum is 35.

The square root of 18218951 is about 4268.3663151140. The cubic root of 18218951 is about 263.1324781832.

Subtracting from 18218951 its reverse (15981281), we obtain a triangular number (2237670 = T₂₁₁₅).

The spelling of 18218951 in words is "eighteen million, two hundred eighteen thousand, nine hundred fifty-one".