28051209 has 12 divisors (see below), whose sum is σ = 40571700. Its totient is φ = 18676224.

The previous prime is 28051193. The next prime is 28051211. The reversal of 28051209 is 90215082.

It can be written as a sum of positive squares in 2 ways, for example, as 18147600 + 9903609 = 4260^2 + 3147^2 .

It is not a de Polignac number, because 28051209 - 2⁴ = 28051193 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28051229) 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, 7537 + ... + 10625.

It is an arithmetic number, because the mean of its divisors is an integer number (3380975).

Almost surely, 2^28051209 is an apocalyptic number.

It is an amenable number.

28051209 is a deficient number, since it is larger than the sum of its proper divisors (12520491).

28051209 is a wasteful number, since it uses less digits than its factorization.

28051209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4104 (or 4101 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 28051209 is about 5296.3392074149. The cubic root of 28051209 is about 303.8439043100.

The spelling of 28051209 in words is "twenty-eight million, fifty-one thousand, two hundred nine".