28161121 has 4 divisors (see below), whose sum is σ = 28196244. Its totient is φ = 28126000.

The previous prime is 28161103. The next prime is 28161139. The reversal of 28161121 is 12116182.

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

It is an interprime number because it is at equal distance from previous prime (28161103) and next prime (28161139).

It can be written as a sum of positive squares in 2 ways, for example, as 4774225 + 23386896 = 2185^2 + 4836^2 .

It is a cyclic number.

It is not a de Polignac number, because 28161121 - 2¹¹ = 28159073 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28161092 and 28161101.

It is not an unprimeable number, because it can be changed into a prime (28161151) 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 in 3 ways as a sum of consecutive naturals, for example, 16330 + ... + 17971.

It is an arithmetic number, because the mean of its divisors is an integer number (7049061).

Almost surely, 2^28161121 is an apocalyptic number.

It is an amenable number.

28161121 is a deficient number, since it is larger than the sum of its proper divisors (35123).

28161121 is an equidigital number, since it uses as much as digits as its factorization.

28161121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35122.

The product of its digits is 192, while the sum is 22.

The square root of 28161121 is about 5306.7052867104. The cubic root of 28161121 is about 304.2402338431.

It can be divided in two parts, 28161 and 121, that added together give a palindrome (28282).

The spelling of 28161121 in words is "twenty-eight million, one hundred sixty-one thousand, one hundred twenty-one".