28118421 has 10 divisors (see below), whose sum is σ = 42004182. Its totient is φ = 18745560.

The previous prime is 28118411. The next prime is 28118471. The reversal of 28118421 is 12481182.

It can be written as a sum of positive squares in only one way, i.e., 16112196 + 12006225 = 4014^2 + 3465^2 .

It is not a de Polignac number, because 28118421 - 2¹⁵ = 28085653 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28118411) 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 9 ways as a sum of consecutive naturals, for example, 173490 + ... + 173651.

Almost surely, 2^28118421 is an apocalyptic number.

It is an amenable number.

28118421 is a deficient number, since it is larger than the sum of its proper divisors (13885761).

28118421 is an equidigital number, since it uses as much as digits as its factorization.

28118421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 347153 (or 347144 counting only the distinct ones).

The product of its digits is 1024, while the sum is 27.

The square root of 28118421 is about 5302.6805485528. The cubic root of 28118421 is about 304.0863854513.

The spelling of 28118421 in words is "twenty-eight million, one hundred eighteen thousand, four hundred twenty-one".