22191721 has 2 divisors, whose sum is σ = 22191722. Its totient is φ = 22191720.

The previous prime is 22191713. The next prime is 22191733. The reversal of 22191721 is 12719122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18147600 + 4044121 = 4260^2 + 2011^2 .

It is a cyclic number.

It is not a de Polignac number, because 22191721 - 2³ = 22191713 is a prime.

It is not a weakly prime, because it can be changed into another prime (22191751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11095860 + 11095861.

It is an arithmetic number, because the mean of its divisors is an integer number (11095861).

Almost surely, 2^22191721 is an apocalyptic number.

It is an amenable number.

22191721 is a deficient number, since it is larger than the sum of its proper divisors (1).

22191721 is an equidigital number, since it uses as much as digits as its factorization.

22191721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 504, while the sum is 25.

The square root of 22191721 is about 4710.8089538847. The cubic root of 22191721 is about 281.0155342366.

The spelling of 22191721 in words is "twenty-two million, one hundred ninety-one thousand, seven hundred twenty-one".