21001221101219 has 2 divisors, whose sum is σ = 21001221101220. Its totient is φ = 21001221101218.

The previous prime is 21001221101213. The next prime is 21001221101221. The reversal of 21001221101219 is 91210112210012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001221101219 is a prime.

It is a super-2 number, since 2×21001221101219² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 21001221101221, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21001221101194 and 21001221101203.

It is not a weakly prime, because it can be changed into another prime (21001221101213) 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, 10500610550609 + 10500610550610.

It is an arithmetic number, because the mean of its divisors is an integer number (10500610550610).

Almost surely, 2^{21001221101219} is an apocalyptic number.

21001221101219 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001221101219 is an equidigital number, since it uses as much as digits as its factorization.

21001221101219 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 23.

The spelling of 21001221101219 in words is "twenty-one trillion, one billion, two hundred twenty-one million, one hundred one thousand, two hundred nineteen".