28720857 has 8 divisors (see below), whose sum is σ = 41775840. Its totient is φ = 17406560.

The previous prime is 28720847. The next prime is 28720891. The reversal of 28720857 is 75802782.

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 28720857 - 2¹⁰ = 28719833 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28720847) 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, 435132 + ... + 435197.

It is an arithmetic number, because the mean of its divisors is an integer number (5221980).

Almost surely, 2^28720857 is an apocalyptic number.

It is an amenable number.

28720857 is a deficient number, since it is larger than the sum of its proper divisors (13054983).

28720857 is a wasteful number, since it uses less digits than its factorization.

28720857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 870343.

The product of its (nonzero) digits is 62720, while the sum is 39.

The square root of 28720857 is about 5359.1843595831. The cubic root of 28720857 is about 306.2427374649.

The spelling of 28720857 in words is "twenty-eight million, seven hundred twenty thousand, eight hundred fifty-seven".