21222765691 has 2 divisors, whose sum is σ = 21222765692. Its totient is φ = 21222765690.

The previous prime is 21222765647. The next prime is 21222765853. The reversal of 21222765691 is 19656722212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21222765691 - 2¹¹ = 21222763643 is a prime.

It is not a weakly prime, because it can be changed into another prime (21222765611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611382845 + 10611382846.

It is an arithmetic number, because the mean of its divisors is an integer number (10611382846).

Almost surely, 2^21222765691 is an apocalyptic number.

21222765691 is a deficient number, since it is larger than the sum of its proper divisors (1).

21222765691 is an equidigital number, since it uses as much as digits as its factorization.

21222765691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 43.

The spelling of 21222765691 in words is "twenty-one billion, two hundred twenty-two million, seven hundred sixty-five thousand, six hundred ninety-one".