18173213 has 4 divisors (see below), whose sum is σ = 18212928. Its totient is φ = 18133500.

The previous prime is 18173203. The next prime is 18173251. The reversal of 18173213 is 31237181.

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, and also an emirpimes, since its reverse is a distinct semiprime: 31237181 = 31 ⋅1007651.

It is a cyclic number.

It is not a de Polignac number, because 18173213 - 2¹² = 18169117 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18173203) 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, 19163 + ... + 20088.

It is an arithmetic number, because the mean of its divisors is an integer number (4553232).

Almost surely, 2^18173213 is an apocalyptic number.

It is an amenable number.

18173213 is a deficient number, since it is larger than the sum of its proper divisors (39715).

18173213 is an equidigital number, since it uses as much as digits as its factorization.

18173213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39714.

The product of its digits is 1008, while the sum is 26.

The square root of 18173213 is about 4263.0051606818. The cubic root of 18173213 is about 262.9120988901.

The spelling of 18173213 in words is "eighteen million, one hundred seventy-three thousand, two hundred thirteen".