18000018221 has 2 divisors, whose sum is σ = 18000018222. Its totient is φ = 18000018220.

The previous prime is 18000018161. The next prime is 18000018233. The reversal of 18000018221 is 12281000081.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17158380100 + 841638121 = 130990^2 + 29011^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18000018221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18000018521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9000009110 + 9000009111.

It is an arithmetic number, because the mean of its divisors is an integer number (9000009111).

Almost surely, 2^18000018221 is an apocalyptic number.

It is an amenable number.

18000018221 is a deficient number, since it is larger than the sum of its proper divisors (1).

18000018221 is an equidigital number, since it uses as much as digits as its factorization.

18000018221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 23.

The spelling of 18000018221 in words is "eighteen billion, eighteen thousand, two hundred twenty-one".