28521005 has 4 divisors (see below), whose sum is σ = 34225212. Its totient is φ = 22816800.

The previous prime is 28521001. The next prime is 28521037. The reversal of 28521005 is 50012582.

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 15697444 + 12823561 = 3962^2 + 3581^2 .

It is not a de Polignac number, because 28521005 - 2² = 28521001 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28521001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2852096 + ... + 2852105.

It is an arithmetic number, because the mean of its divisors is an integer number (8556303).

Almost surely, 2^28521005 is an apocalyptic number.

It is an amenable number.

28521005 is a deficient number, since it is larger than the sum of its proper divisors (5704207).

28521005 is an equidigital number, since it uses as much as digits as its factorization.

28521005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5704206.

The product of its (nonzero) digits is 800, while the sum is 23.

The square root of 28521005 is about 5340.5060621630. The cubic root of 28521005 is about 305.5307608653.

Adding to 28521005 its reverse (50012582), we get a palindrome (78533587).

The spelling of 28521005 in words is "twenty-eight million, five hundred twenty-one thousand, five".