21991803444269 has 2 divisors, whose sum is σ = 21991803444270. Its totient is φ = 21991803444268.

The previous prime is 21991803444253. The next prime is 21991803444271. The reversal of 21991803444269 is 96244430819912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16787154367369 + 5204649076900 = 4097213^2 + 2281370^2 .

It is a cyclic number.

It is not a de Polignac number, because 21991803444269 - 2⁴ = 21991803444253 is a prime.

It is a super-2 number, since 2×21991803444269² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 21991803444271, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21991803444239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10995901722134 + 10995901722135.

It is an arithmetic number, because the mean of its divisors is an integer number (10995901722135).

Almost surely, 2^{21991803444269} is an apocalyptic number.

It is an amenable number.

21991803444269 is a deficient number, since it is larger than the sum of its proper divisors (1).

21991803444269 is an equidigital number, since it uses as much as digits as its factorization.

21991803444269 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 26873856, while the sum is 62.

The spelling of 21991803444269 in words is "twenty-one trillion, nine hundred ninety-one billion, eight hundred three million, four hundred forty-four thousand, two hundred sixty-nine".