18445993 has 4 divisors (see below), whose sum is σ = 18486468. Its totient is φ = 18405520.

The previous prime is 18445981. The next prime is 18446027. The reversal of 18445993 is 39954481.

It is a happy number.

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 6906384 + 11539609 = 2628^2 + 3397^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18445993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18445963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19546 + ... + 20467.

It is an arithmetic number, because the mean of its divisors is an integer number (4621617).

Almost surely, 2^18445993 is an apocalyptic number.

It is an amenable number.

18445993 is a deficient number, since it is larger than the sum of its proper divisors (40475).

18445993 is an equidigital number, since it uses as much as digits as its factorization.

18445993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40474.

The product of its digits is 155520, while the sum is 43.

The square root of 18445993 is about 4294.8798586224. The cubic root of 18445993 is about 264.2210088768.

The spelling of 18445993 in words is "eighteen million, four hundred forty-five thousand, nine hundred ninety-three".