18190993 has 4 divisors (see below), whose sum is σ = 18489268. Its totient is φ = 17892720.

The previous prime is 18190979. The next prime is 18191023. The reversal of 18190993 is 39909181.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8809024 + 9381969 = 2968^2 + 3063^2 .

It is a cyclic number.

It is not a de Polignac number, because 18190993 - 2⁹ = 18190481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18190903) 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, 149046 + ... + 149167.

It is an arithmetic number, because the mean of its divisors is an integer number (4622317).

Almost surely, 2^18190993 is an apocalyptic number.

It is an amenable number.

18190993 is a deficient number, since it is larger than the sum of its proper divisors (298275).

18190993 is an equidigital number, since it uses as much as digits as its factorization.

18190993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 298274.

The product of its (nonzero) digits is 17496, while the sum is 40.

The square root of 18190993 is about 4265.0900342197. The cubic root of 18190993 is about 262.9978121038.

The spelling of 18190993 in words is "eighteen million, one hundred ninety thousand, nine hundred ninety-three".