18356993 has 4 divisors (see below), whose sum is σ = 18589440. Its totient is φ = 18124548.

The previous prime is 18356981. The next prime is 18356999. The reversal of 18356993 is 39965381.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18356993 - 2⁴ = 18356977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18356999) 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, 116105 + ... + 116262.

It is an arithmetic number, because the mean of its divisors is an integer number (4647360).

Almost surely, 2^18356993 is an apocalyptic number.

It is an amenable number.

18356993 is a deficient number, since it is larger than the sum of its proper divisors (232447).

18356993 is an equidigital number, since it uses as much as digits as its factorization.

18356993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232446.

The product of its digits is 174960, while the sum is 44.

The square root of 18356993 is about 4284.5061559064. The cubic root of 18356993 is about 263.7953772917.

The spelling of 18356993 in words is "eighteen million, three hundred fifty-six thousand, nine hundred ninety-three".