18721223 has 4 divisors (see below), whose sum is σ = 19227240. Its totient is φ = 18215208.

The previous prime is 18721217. The next prime is 18721229. The reversal of 18721223 is 32212781.

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

It is an interprime number because it is at equal distance from previous prime (18721217) and next prime (18721229).

It is a cyclic number.

It is not a de Polignac number, because 18721223 - 2⁶ = 18721159 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18721192 and 18721201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18721229) 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, 252953 + ... + 253026.

It is an arithmetic number, because the mean of its divisors is an integer number (4806810).

Almost surely, 2^18721223 is an apocalyptic number.

18721223 is a deficient number, since it is larger than the sum of its proper divisors (506017).

18721223 is an equidigital number, since it uses as much as digits as its factorization.

18721223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 506016.

The product of its digits is 1344, while the sum is 26.

The square root of 18721223 is about 4326.8028612360. The cubic root of 18721223 is about 265.5286610356.

The spelling of 18721223 in words is "eighteen million, seven hundred twenty-one thousand, two hundred twenty-three".