28403217 has 10 divisors (see below), whose sum is σ = 42429618. Its totient is φ = 18935424.

The previous prime is 28403213. The next prime is 28403237. The reversal of 28403217 is 71230482.

It can be written as a sum of positive squares in only one way, i.e., 26224641 + 2178576 = 5121^2 + 1476^2 .

It is not a de Polignac number, because 28403217 - 2² = 28403213 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (28403213) 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 9 ways as a sum of consecutive naturals, for example, 175248 + ... + 175409.

Almost surely, 2^28403217 is an apocalyptic number.

28403217 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

28403217 is a deficient number, since it is larger than the sum of its proper divisors (14026401).

28403217 is an equidigital number, since it uses as much as digits as its factorization.

28403217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350669 (or 350660 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 28403217 is about 5329.4668588894. The cubic root of 28403217 is about 305.1095799036.

Adding to 28403217 its reverse (71230482), we get a palindrome (99633699).

The spelling of 28403217 in words is "twenty-eight million, four hundred three thousand, two hundred seventeen".