28013905 has 4 divisors (see below), whose sum is σ = 33616692. Its totient is φ = 22411120.

The previous prime is 28013899. The next prime is 28013917. The reversal of 28013905 is 50931082.

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 18766224 + 9247681 = 4332^2 + 3041^2 .

It is not a de Polignac number, because 28013905 - 2⁵ = 28013873 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2801386 + ... + 2801395.

It is an arithmetic number, because the mean of its divisors is an integer number (8404173).

Almost surely, 2^28013905 is an apocalyptic number.

It is an amenable number.

28013905 is a deficient number, since it is larger than the sum of its proper divisors (5602787).

28013905 is an equidigital number, since it uses as much as digits as its factorization.

28013905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5602786.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 28013905 is about 5292.8163580461. The cubic root of 28013905 is about 303.7091552614.

Adding to 28013905 its reverse (50931082), we get a palindrome (78944987).

The spelling of 28013905 in words is "twenty-eight million, thirteen thousand, nine hundred five".