21221202109 has 2 divisors, whose sum is σ = 21221202110. Its totient is φ = 21221202108.

The previous prime is 21221202089. The next prime is 21221202131. The reversal of 21221202109 is 90120212212.

It is an a-pointer prime, because the next prime (21221202131) can be obtained adding 21221202109 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19250730009 + 1970472100 = 138747^2 + 44390^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221202109 - 2⁵ = 21221202077 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21221202109.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221212109) 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, 10610601054 + 10610601055.

It is an arithmetic number, because the mean of its divisors is an integer number (10610601055).

Almost surely, 2^21221202109 is an apocalyptic number.

It is an amenable number.

21221202109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221202109 is an equidigital number, since it uses as much as digits as its factorization.

21221202109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 22.

The spelling of 21221202109 in words is "twenty-one billion, two hundred twenty-one million, two hundred two thousand, one hundred nine".