21221212069 has 2 divisors, whose sum is σ = 21221212070. Its totient is φ = 21221212068.

The previous prime is 21221212049. The next prime is 21221212079. The reversal of 21221212069 is 96021212212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21045304900 + 175907169 = 145070^2 + 13263^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221212069 is a prime.

It is a super-2 number, since 2×21221212069² (a number of 21 digits) contains 22 as substring.

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 polite number, since it can be written as a sum of consecutive naturals, namely, 10610606034 + 10610606035.

It is an arithmetic number, because the mean of its divisors is an integer number (10610606035).

Almost surely, 2^21221212069 is an apocalyptic number.

It is an amenable number.

21221212069 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221212069 is an equidigital number, since it uses as much as digits as its factorization.

21221212069 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

The spelling of 21221212069 in words is "twenty-one billion, two hundred twenty-one million, two hundred twelve thousand, sixty-nine".