28705913 has 8 divisors (see below), whose sum is σ = 29521800. Its totient is φ = 27900288.

The previous prime is 28705891. The next prime is 28705921. The reversal of 28705913 is 31950782.

It can be written as a sum of positive squares in 4 ways, for example, as 5396329 + 23309584 = 2323^2 + 4828^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28705913 - 2⁸ = 28705657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28705933) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3293 + ... + 8261.

It is an arithmetic number, because the mean of its divisors is an integer number (3690225).

Almost surely, 2^28705913 is an apocalyptic number.

It is an amenable number.

28705913 is a deficient number, since it is larger than the sum of its proper divisors (815887).

28705913 is a wasteful number, since it uses less digits than its factorization.

28705913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5131.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 28705913 is about 5357.7899361584. The cubic root of 28705913 is about 306.1896136387.

The spelling of 28705913 in words is "twenty-eight million, seven hundred five thousand, nine hundred thirteen".