21919109 has 2 divisors, whose sum is σ = 21919110. Its totient is φ = 21919108.

The previous prime is 21919097. The next prime is 21919111. The reversal of 21919109 is 90191912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20702500 + 1216609 = 4550^2 + 1103^2 .

It is a cyclic number.

It is not a de Polignac number, because 21919109 - 2¹² = 21915013 is a prime.

Together with 21919111, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21919129) 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, 10959554 + 10959555.

It is an arithmetic number, because the mean of its divisors is an integer number (10959555).

Almost surely, 2^21919109 is an apocalyptic number.

It is an amenable number.

21919109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21919109 is an equidigital number, since it uses as much as digits as its factorization.

21919109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 21919109 is about 4681.7848092368. The cubic root of 21919109 is about 279.8600874120.

The spelling of 21919109 in words is "twenty-one million, nine hundred nineteen thousand, one hundred nine".