18766005221 has 2 divisors, whose sum is σ = 18766005222. Its totient is φ = 18766005220.

The previous prime is 18766005191. The next prime is 18766005337. The reversal of 18766005221 is 12250066781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16837917121 + 1928088100 = 129761^2 + 43910^2 .

It is an emirp because it is prime and its reverse (12250066781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18766005221 - 2¹⁸ = 18765743077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18766005121) 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, 9383002610 + 9383002611.

It is an arithmetic number, because the mean of its divisors is an integer number (9383002611).

Almost surely, 2^18766005221 is an apocalyptic number.

It is an amenable number.

18766005221 is a deficient number, since it is larger than the sum of its proper divisors (1).

18766005221 is an equidigital number, since it uses as much as digits as its factorization.

18766005221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 38.

The spelling of 18766005221 in words is "eighteen billion, seven hundred sixty-six million, five thousand, two hundred twenty-one".