28221351 has 4 divisors (see below), whose sum is σ = 37628472. Its totient is φ = 18814232.

The previous prime is 28221337. The next prime is 28221353. The reversal of 28221351 is 15312282.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28221351 - 2¹⁵ = 28188583 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28221353) 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 in 3 ways as a sum of consecutive naturals, for example, 4703556 + ... + 4703561.

It is an arithmetic number, because the mean of its divisors is an integer number (9407118).

Almost surely, 2^28221351 is an apocalyptic number.

28221351 is a deficient number, since it is larger than the sum of its proper divisors (9407121).

28221351 is an equidigital number, since it uses as much as digits as its factorization.

28221351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9407120.

The product of its digits is 960, while the sum is 24.

The square root of 28221351 is about 5312.3771515208. The cubic root of 28221351 is about 304.4569787770.

The spelling of 28221351 in words is "twenty-eight million, two hundred twenty-one thousand, three hundred fifty-one".