28124221 has 2 divisors, whose sum is σ = 28124222. Its totient is φ = 28124220.

The previous prime is 28124209. The next prime is 28124293. The reversal of 28124221 is 12242182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25100100 + 3024121 = 5010^2 + 1739^2 .

It is a cyclic number.

It is not a de Polignac number, because 28124221 - 2⁷ = 28124093 is a prime.

It is a super-3 number, since 3×28124221³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 28124192 and 28124201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28122221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14062110 + 14062111.

It is an arithmetic number, because the mean of its divisors is an integer number (14062111).

Almost surely, 2^28124221 is an apocalyptic number.

It is an amenable number.

28124221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28124221 is an equidigital number, since it uses as much as digits as its factorization.

28124221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 512, while the sum is 22.

The square root of 28124221 is about 5303.2274135662. The cubic root of 28124221 is about 304.1072920281.

The spelling of 28124221 in words is "twenty-eight million, one hundred twenty-four thousand, two hundred twenty-one".