21642221291 has 2 divisors, whose sum is σ = 21642221292. Its totient is φ = 21642221290.

The previous prime is 21642221273. The next prime is 21642221323. The reversal of 21642221291 is 19212224612.

It is an a-pointer prime, because the next prime (21642221323) can be obtained adding 21642221291 to its sum of digits (32).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21642221291 - 2¹⁴ = 21642204907 is a prime.

It is a super-2 number, since 2×21642221291² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21642221191) 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, 10821110645 + 10821110646.

It is an arithmetic number, because the mean of its divisors is an integer number (10821110646).

Almost surely, 2^21642221291 is an apocalyptic number.

21642221291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642221291 is an equidigital number, since it uses as much as digits as its factorization.

21642221291 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 32.

The spelling of 21642221291 in words is "twenty-one billion, six hundred forty-two million, two hundred twenty-one thousand, two hundred ninety-one".