16668339221 has 2 divisors, whose sum is σ = 16668339222. Its totient is φ = 16668339220.

The previous prime is 16668339217. The next prime is 16668339283. The reversal of 16668339221 is 12293386661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14796046321 + 1872292900 = 121639^2 + 43270^2 .

It is a cyclic number.

It is not a de Polignac number, because 16668339221 - 2² = 16668339217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16668339521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8334169610 + 8334169611.

It is an arithmetic number, because the mean of its divisors is an integer number (8334169611).

Almost surely, 2^16668339221 is an apocalyptic number.

It is an amenable number.

16668339221 is a deficient number, since it is larger than the sum of its proper divisors (1).

16668339221 is an equidigital number, since it uses as much as digits as its factorization.

16668339221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 559872, while the sum is 47.

The spelling of 16668339221 in words is "sixteen billion, six hundred sixty-eight million, three hundred thirty-nine thousand, two hundred twenty-one".