18355994 has 4 divisors (see below), whose sum is σ = 27533994. Its totient is φ = 9177996.

The previous prime is 18355993. The next prime is 18356003. The reversal of 18355994 is 49955381.

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: 49955381 = 7 ⋅7136483.

It can be written as a sum of positive squares in only one way, i.e., 14100025 + 4255969 = 3755^2 + 2063^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18355993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4588997 + ... + 4589000.

Almost surely, 2^18355994 is an apocalyptic number.

18355994 is a deficient number, since it is larger than the sum of its proper divisors (9178000).

18355994 is an equidigital number, since it uses as much as digits as its factorization.

18355994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9177999.

The product of its digits is 194400, while the sum is 44.

The square root of 18355994 is about 4284.3895714559. The cubic root of 18355994 is about 263.7905918972.

The spelling of 18355994 in words is "eighteen million, three hundred fifty-five thousand, nine hundred ninety-four".