28078209 has 12 divisors (see below), whose sum is σ = 41113956. Its totient is φ = 18461952.

The previous prime is 28078189. The next prime is 28078229. The reversal of 28078209 is 90287082.

It is an interprime number because it is at equal distance from previous prime (28078189) and next prime (28078229).

It can be written as a sum of positive squares in 2 ways, for example, as 18249984 + 9828225 = 4272^2 + 3135^2 .

It is not a de Polignac number, because 28078209 - 2⁷ = 28078081 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28078229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20712 + ... + 22025.

It is an arithmetic number, because the mean of its divisors is an integer number (3426163).

Almost surely, 2^28078209 is an apocalyptic number.

It is an amenable number.

28078209 is a deficient number, since it is larger than the sum of its proper divisors (13035747).

28078209 is a wasteful number, since it uses less digits than its factorization.

28078209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42816 (or 42813 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 28078209 is about 5298.8875247546. The cubic root of 28078209 is about 303.9413588702.

The spelling of 28078209 in words is "twenty-eight million, seventy-eight thousand, two hundred nine".