21221000191 has 2 divisors, whose sum is σ = 21221000192. Its totient is φ = 21221000190.

The previous prime is 21221000179. The next prime is 21221000201. The reversal of 21221000191 is 19100012212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21221000191 - 2¹⁷ = 21220869119 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221000131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610500095 + 10610500096.

It is an arithmetic number, because the mean of its divisors is an integer number (10610500096).

Almost surely, 2^21221000191 is an apocalyptic number.

21221000191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221000191 is an equidigital number, since it uses as much as digits as its factorization.

21221000191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 19.

The spelling of 21221000191 in words is "twenty-one billion, two hundred twenty-one million, one hundred ninety-one", and thus it is an aban number.