28643905 has 4 divisors (see below), whose sum is σ = 34372692. Its totient is φ = 22915120.

The previous prime is 28643897. The next prime is 28643917. The reversal of 28643905 is 50934682.

It is a Cunningham number, because it is equal to 5352²+1.

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 10316944 + 18326961 = 3212^2 + 4281^2 .

It is not a de Polignac number, because 28643905 - 2³ = 28643897 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, 2864386 + ... + 2864395.

It is an arithmetic number, because the mean of its divisors is an integer number (8593173).

Almost surely, 2^28643905 is an apocalyptic number.

It is an amenable number.

28643905 is a deficient number, since it is larger than the sum of its proper divisors (5728787).

28643905 is an equidigital number, since it uses as much as digits as its factorization.

28643905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5728786.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 28643905 is about 5352.0000934230. Note that the first 4 decimals coincide. The cubic root of 28643905 is about 305.9689867041.

The spelling of 28643905 in words is "twenty-eight million, six hundred forty-three thousand, nine hundred five".