21919408917449 has 2 divisors, whose sum is σ = 21919408917450. Its totient is φ = 21919408917448.

The previous prime is 21919408917383. The next prime is 21919408917451. The reversal of 21919408917449 is 94471980491912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21766824933049 + 152583984400 = 4665493^2 + 390620^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21919408917449 is a prime.

Together with 21919408917451, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21919408517449) 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, 10959704458724 + 10959704458725.

It is an arithmetic number, because the mean of its divisors is an integer number (10959704458725).

Almost surely, 2^{21919408917449} is an apocalyptic number.

It is an amenable number.

21919408917449 is a deficient number, since it is larger than the sum of its proper divisors (1).

21919408917449 is an equidigital number, since it uses as much as digits as its factorization.

21919408917449 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 47029248, while the sum is 68.

The spelling of 21919408917449 in words is "twenty-one trillion, nine hundred nineteen billion, four hundred eight million, nine hundred seventeen thousand, four hundred forty-nine".