221636754444221 has 2 divisors, whose sum is σ = 221636754444222. Its totient is φ = 221636754444220.

The previous prime is 221636754444109. The next prime is 221636754444247. The reversal of 221636754444221 is 122444457636122.

221636754444221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 130310329776025 + 91326424668196 = 11415355^2 + 9556486^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221636754444221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221636754444271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110818377222110 + 110818377222111.

It is an arithmetic number, because the mean of its divisors is an integer number (110818377222111).

Almost surely, 2^{221636754444221} is an apocalyptic number.

It is an amenable number.

221636754444221 is a deficient number, since it is larger than the sum of its proper divisors (1).

221636754444221 is an equidigital number, since it uses as much as digits as its factorization.

221636754444221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15482880, while the sum is 53.

The spelling of 221636754444221 in words is "two hundred twenty-one trillion, six hundred thirty-six billion, seven hundred fifty-four million, four hundred forty-four thousand, two hundred twenty-one".