28705861 has 4 divisors (see below), whose sum is σ = 29316672. Its totient is φ = 28095052.

The previous prime is 28705847. The next prime is 28705891. The reversal of 28705861 is 16850782.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28705861 - 2⁵ = 28705829 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28705861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28705891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 305335 + ... + 305428.

It is an arithmetic number, because the mean of its divisors is an integer number (7329168).

Almost surely, 2^28705861 is an apocalyptic number.

It is an amenable number.

28705861 is a deficient number, since it is larger than the sum of its proper divisors (610811).

28705861 is an equidigital number, since it uses as much as digits as its factorization.

28705861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610810.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 28705861 is about 5357.7850834090. The cubic root of 28705861 is about 306.1894287538.

The spelling of 28705861 in words is "twenty-eight million, seven hundred five thousand, eight hundred sixty-one".