18197321 has 2 divisors, whose sum is σ = 18197322. Its totient is φ = 18197320.

The previous prime is 18197287. The next prime is 18197323. The reversal of 18197321 is 12379181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18181696 + 15625 = 4264^2 + 125^2 .

It is an emirp because it is prime and its reverse (12379181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18197321 - 2¹⁴ = 18180937 is a prime.

It is a super-2 number, since 2×18197321² = 662284983154082, which contains 22 as substring.

Together with 18197323, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18197323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9098660 + 9098661.

It is an arithmetic number, because the mean of its divisors is an integer number (9098661).

Almost surely, 2^18197321 is an apocalyptic number.

It is an amenable number.

18197321 is a deficient number, since it is larger than the sum of its proper divisors (1).

18197321 is an equidigital number, since it uses as much as digits as its factorization.

18197321 is an evil number, because the sum of its binary digits is even.

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

The square root of 18197321 is about 4265.8318063421. The cubic root of 18197321 is about 263.0283044325.

The spelling of 18197321 in words is "eighteen million, one hundred ninety-seven thousand, three hundred twenty-one".