21922009 has 2 divisors, whose sum is σ = 21922010. Its totient is φ = 21922008.

The previous prime is 21922007. The next prime is 21922037. The reversal of 21922009 is 90022912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15015625 + 6906384 = 3875^2 + 2628^2 .

It is a cyclic number.

It is not a de Polignac number, because 21922009 - 2¹ = 21922007 is a prime.

Together with 21922007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21922007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10961004 + 10961005.

It is an arithmetic number, because the mean of its divisors is an integer number (10961005).

Almost surely, 2^21922009 is an apocalyptic number.

It is an amenable number.

21922009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21922009 is an equidigital number, since it uses as much as digits as its factorization.

21922009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 21922009 is about 4682.0945099389. The cubic root of 21922009 is about 279.8724291311.

The spelling of 21922009 in words is "twenty-one million, nine hundred twenty-two thousand, nine".