191768221 has 2 divisors, whose sum is σ = 191768222. Its totient is φ = 191768220.

The previous prime is 191768219. The next prime is 191768243. The reversal of 191768221 is 122867191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 109956196 + 81812025 = 10486^2 + 9045^2 .

It is a cyclic number.

It is not a de Polignac number, because 191768221 - 2¹ = 191768219 is a prime.

Together with 191768219, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191768281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95884110 + 95884111.

It is an arithmetic number, because the mean of its divisors is an integer number (95884111).

Almost surely, 2^191768221 is an apocalyptic number.

It is an amenable number.

191768221 is a deficient number, since it is larger than the sum of its proper divisors (1).

191768221 is an equidigital number, since it uses as much as digits as its factorization.

191768221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 37.

The square root of 191768221 is about 13848.0403306750. The cubic root of 191768221 is about 576.6675935625.

The spelling of 191768221 in words is "one hundred ninety-one million, seven hundred sixty-eight thousand, two hundred twenty-one".