28127221 has 2 divisors, whose sum is σ = 28127222. Its totient is φ = 28127220.

The previous prime is 28127207. The next prime is 28127249. The reversal of 28127221 is 12272182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21288996 + 6838225 = 4614^2 + 2615^2 .

It is a cyclic number.

It is not a de Polignac number, because 28127221 - 2¹¹ = 28125173 is a prime.

It is a super-2 number, since 2×28127221² = 1582281122365682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28127251) 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, 14063610 + 14063611.

It is an arithmetic number, because the mean of its divisors is an integer number (14063611).

Almost surely, 2^28127221 is an apocalyptic number.

It is an amenable number.

28127221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28127221 is an equidigital number, since it uses as much as digits as its factorization.

28127221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 896, while the sum is 25.

The square root of 28127221 is about 5303.5102526534. The cubic root of 28127221 is about 304.1181046469.

The spelling of 28127221 in words is "twenty-eight million, one hundred twenty-seven thousand, two hundred twenty-one".