21244245221 has 2 divisors, whose sum is σ = 21244245222. Its totient is φ = 21244245220.

The previous prime is 21244245203. The next prime is 21244245233. The reversal of 21244245221 is 12254244212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15316785121 + 5927460100 = 123761^2 + 76990^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21244245221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21244245271) 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, 10622122610 + 10622122611.

It is an arithmetic number, because the mean of its divisors is an integer number (10622122611).

Almost surely, 2^21244245221 is an apocalyptic number.

It is an amenable number.

21244245221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21244245221 is an equidigital number, since it uses as much as digits as its factorization.

21244245221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10240, while the sum is 29.

Adding to 21244245221 its reverse (12254244212), we get a palindrome (33498489433).

The spelling of 21244245221 in words is "twenty-one billion, two hundred forty-four million, two hundred forty-five thousand, two hundred twenty-one".