18557818 has 4 divisors (see below), whose sum is σ = 27836730. Its totient is φ = 9278908.

The previous prime is 18557807. The next prime is 18557821. The reversal of 18557818 is 81875581.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81875581 = 1409 ⋅58109.

It can be written as a sum of positive squares in only one way, i.e., 18550249 + 7569 = 4307^2 + 87^2 .

It is a super-2 number, since 2×18557818² = 688785217842248, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4639453 + ... + 4639456.

Almost surely, 2^18557818 is an apocalyptic number.

18557818 is a deficient number, since it is larger than the sum of its proper divisors (9278912).

18557818 is an equidigital number, since it uses as much as digits as its factorization.

18557818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9278911.

The product of its digits is 89600, while the sum is 43.

The square root of 18557818 is about 4307.8785962466. The cubic root of 18557818 is about 264.7538618756.

The spelling of 18557818 in words is "eighteen million, five hundred fifty-seven thousand, eight hundred eighteen".