28002805 has 4 divisors (see below), whose sum is σ = 33603372. Its totient is φ = 22402240.

The previous prime is 28002803. The next prime is 28002809. The reversal of 28002805 is 50820082.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8844676 + 19158129 = 2974^2 + 4377^2 .

It is not a de Polignac number, because 28002805 - 2¹ = 28002803 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28002805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28002803) 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, 2800276 + ... + 2800285.

It is an arithmetic number, because the mean of its divisors is an integer number (8400843).

Almost surely, 2^28002805 is an apocalyptic number.

It is an amenable number.

28002805 is a deficient number, since it is larger than the sum of its proper divisors (5600567).

28002805 is an equidigital number, since it uses as much as digits as its factorization.

28002805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5600566.

The product of its (nonzero) digits is 1280, while the sum is 25.

The square root of 28002805 is about 5291.7676630782. The cubic root of 28002805 is about 303.6690368872.

Adding to 28002805 its reverse (50820082), we get a palindrome (78822887).

The spelling of 28002805 in words is "twenty-eight million, two thousand, eight hundred five".