21221212079 has 2 divisors, whose sum is σ = 21221212080. Its totient is φ = 21221212078.

The previous prime is 21221212069. The next prime is 21221212109. The reversal of 21221212079 is 97021212212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221212079 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221212049) 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, 10610606039 + 10610606040.

It is an arithmetic number, because the mean of its divisors is an integer number (10610606040).

Almost surely, 2^21221212079 is an apocalyptic number.

21221212079 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221212079 is an equidigital number, since it uses as much as digits as its factorization.

21221212079 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 29.

The spelling of 21221212079 in words is "twenty-one billion, two hundred twenty-one million, two hundred twelve thousand, seventy-nine".