18117973 has 2 divisors, whose sum is σ = 18117974. Its totient is φ = 18117972.

The previous prime is 18117959. The next prime is 18117977. The reversal of 18117973 is 37971181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17489124 + 628849 = 4182^2 + 793^2 .

It is an emirp because it is prime and its reverse (37971181) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18117973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18117977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9058986 + 9058987.

It is an arithmetic number, because the mean of its divisors is an integer number (9058987).

Almost surely, 2^18117973 is an apocalyptic number.

It is an amenable number.

18117973 is a deficient number, since it is larger than the sum of its proper divisors (1).

18117973 is an equidigital number, since it uses as much as digits as its factorization.

18117973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10584, while the sum is 37.

The square root of 18117973 is about 4256.5212321801. The cubic root of 18117973 is about 262.6454426050.

The spelling of 18117973 in words is "eighteen million, one hundred seventeen thousand, nine hundred seventy-three".