28209813 has 16 divisors (see below), whose sum is σ = 39705600. Its totient is φ = 17766000.

The previous prime is 28209803. The next prime is 28209821. The reversal of 28209813 is 31890282.

It is not a de Polignac number, because 28209813 - 2⁹ = 28209301 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28209803) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37188 + ... + 37938.

It is an arithmetic number, because the mean of its divisors is an integer number (2481600).

Almost surely, 2^28209813 is an apocalyptic number.

It is an amenable number.

28209813 is a deficient number, since it is larger than the sum of its proper divisors (11495787).

28209813 is a wasteful number, since it uses less digits than its factorization.

28209813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1432.

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 28209813 is about 5311.2910859790. The cubic root of 28209813 is about 304.4154817859.

The spelling of 28209813 in words is "twenty-eight million, two hundred nine thousand, eight hundred thirteen".