28708261 has 4 divisors (see below), whose sum is σ = 28780972. Its totient is φ = 28635552.

The previous prime is 28708243. The next prime is 28708313. The reversal of 28708261 is 16280782.

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 23824161 + 4884100 = 4881^2 + 2210^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28708261 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 (28708661) 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, 35760 + ... + 36553.

It is an arithmetic number, because the mean of its divisors is an integer number (7195243).

Almost surely, 2^28708261 is an apocalyptic number.

It is an amenable number.

28708261 is a deficient number, since it is larger than the sum of its proper divisors (72711).

28708261 is an equidigital number, since it uses as much as digits as its factorization.

28708261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72710.

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 28708261 is about 5358.0090518774. The cubic root of 28708261 is about 306.1979616704.

The spelling of 28708261 in words is "twenty-eight million, seven hundred eight thousand, two hundred sixty-one".