28038209 has 4 divisors (see below), whose sum is σ = 28077504. Its totient is φ = 27998916.

The previous prime is 28038191. The next prime is 28038211. The reversal of 28038209 is 90283082.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90283082 = 2 ⋅45141541.

It is a cyclic number.

It is not a de Polignac number, because 28038209 - 2¹² = 28034113 is a prime.

It is a super-2 number, since 2×28038209² = 1572282327855362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28038239) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18557 + ... + 20010.

It is an arithmetic number, because the mean of its divisors is an integer number (7019376).

Almost surely, 2^28038209 is an apocalyptic number.

It is an amenable number.

28038209 is a deficient number, since it is larger than the sum of its proper divisors (39295).

28038209 is an equidigital number, since it uses as much as digits as its factorization.

28038209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39294.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 28038209 is about 5295.1118024080. Note that the first 3 decimals coincide. The cubic root of 28038209 is about 303.7969594397.

The spelling of 28038209 in words is "twenty-eight million, thirty-eight thousand, two hundred nine".