21420212291 has 2 divisors, whose sum is σ = 21420212292. Its totient is φ = 21420212290.

The previous prime is 21420212273. The next prime is 21420212293. The reversal of 21420212291 is 19221202412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21420212291 is a prime.

Together with 21420212293, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21420212291.

It is not a weakly prime, because it can be changed into another prime (21420212293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710106145 + 10710106146.

It is an arithmetic number, because the mean of its divisors is an integer number (10710106146).

Almost surely, 2^21420212291 is an apocalyptic number.

21420212291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420212291 is an equidigital number, since it uses as much as digits as its factorization.

21420212291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 26.

The spelling of 21420212291 in words is "twenty-one billion, four hundred twenty million, two hundred twelve thousand, two hundred ninety-one".