191810969221 has 2 divisors, whose sum is σ = 191810969222. Its totient is φ = 191810969220.

The previous prime is 191810969191. The next prime is 191810969261. The reversal of 191810969221 is 122969018191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 152404352100 + 39406617121 = 390390^2 + 198511^2 .

It is a cyclic number.

It is not a de Polignac number, because 191810969221 - 2⁹ = 191810968709 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191810969261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95905484610 + 95905484611.

It is an arithmetic number, because the mean of its divisors is an integer number (95905484611).

Almost surely, 2^191810969221 is an apocalyptic number.

It is an amenable number.

191810969221 is a deficient number, since it is larger than the sum of its proper divisors (1).

191810969221 is an equidigital number, since it uses as much as digits as its factorization.

191810969221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 139968, while the sum is 49.

The spelling of 191810969221 in words is "one hundred ninety-one billion, eight hundred ten million, nine hundred sixty-nine thousand, two hundred twenty-one".