28504244221 has 2 divisors, whose sum is σ = 28504244222. Its totient is φ = 28504244220.

The previous prime is 28504244183. The next prime is 28504244257. The reversal of 28504244221 is 12244240582.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23689827225 + 4814416996 = 153915^2 + 69386^2 .

It is a cyclic number.

It is not a de Polignac number, because 28504244221 - 2²⁹ = 27967373309 is a prime.

It is a super-2 number, since 2×28504244221² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28504244521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14252122110 + 14252122111.

It is an arithmetic number, because the mean of its divisors is an integer number (14252122111).

Almost surely, 2^28504244221 is an apocalyptic number.

It is an amenable number.

28504244221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28504244221 is an equidigital number, since it uses as much as digits as its factorization.

28504244221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40960, while the sum is 34.

The spelling of 28504244221 in words is "twenty-eight billion, five hundred four million, two hundred forty-four thousand, two hundred twenty-one".