18173921 has 2 divisors, whose sum is σ = 18173922. Its totient is φ = 18173920.

The previous prime is 18173879. The next prime is 18173957. The reversal of 18173921 is 12937181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16321600 + 1852321 = 4040^2 + 1361^2 .

It is a cyclic number.

It is not a de Polignac number, because 18173921 - 2¹⁰ = 18172897 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18173021) 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 as a sum of consecutive naturals, namely, 9086960 + 9086961.

It is an arithmetic number, because the mean of its divisors is an integer number (9086961).

Almost surely, 2^18173921 is an apocalyptic number.

It is an amenable number.

18173921 is a deficient number, since it is larger than the sum of its proper divisors (1).

18173921 is an equidigital number, since it uses as much as digits as its factorization.

18173921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 32.

The square root of 18173921 is about 4263.0881998851. The cubic root of 18173921 is about 262.9155130607.

The spelling of 18173921 in words is "eighteen million, one hundred seventy-three thousand, nine hundred twenty-one".