28123745 has 32 divisors (see below), whose sum is σ = 38060064. Its totient is φ = 19814400.

The previous prime is 28123723. The next prime is 28123747. The reversal of 28123745 is 54732182.

It can be written as a sum of positive squares in 16 ways, for example, as 19989841 + 8133904 = 4471^2 + 2852^2 .

It is not a de Polignac number, because 28123745 - 2⁸ = 28123489 is a prime.

It is a Smith number, since the sum of its digits (32) 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 Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28123747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 162479 + ... + 162651.

It is an arithmetic number, because the mean of its divisors is an integer number (1189377).

Almost surely, 2^28123745 is an apocalyptic number.

It is an amenable number.

28123745 is a deficient number, since it is larger than the sum of its proper divisors (9936319).

28123745 is a wasteful number, since it uses less digits than its factorization.

28123745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 293.

The product of its digits is 13440, while the sum is 32.

The square root of 28123745 is about 5303.1825350444. The cubic root of 28123745 is about 304.1055763552.

The spelling of 28123745 in words is "twenty-eight million, one hundred twenty-three thousand, seven hundred forty-five".