18720173 has 2 divisors, whose sum is σ = 18720174. Its totient is φ = 18720172.

The previous prime is 18720083. The next prime is 18720197. The reversal of 18720173 is 37102781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16024009 + 2696164 = 4003^2 + 1642^2 .

It is an emirp because it is prime and its reverse (37102781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18720173 - 2⁸ = 18719917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18720673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9360086 + 9360087.

It is an arithmetic number, because the mean of its divisors is an integer number (9360087).

Almost surely, 2^18720173 is an apocalyptic number.

It is an amenable number.

18720173 is a deficient number, since it is larger than the sum of its proper divisors (1).

18720173 is an equidigital number, since it uses as much as digits as its factorization.

18720173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2352, while the sum is 29.

The square root of 18720173 is about 4326.6815228302. The cubic root of 18720173 is about 265.5236967889.

The spelling of 18720173 in words is "eighteen million, seven hundred twenty thousand, one hundred seventy-three".