28217857 has 4 divisors (see below), whose sum is σ = 28381140. Its totient is φ = 28054576.

The previous prime is 28217851. The next prime is 28217863. The reversal of 28217857 is 75871282.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (28217851) and next prime (28217863).

It can be written as a sum of positive squares in 2 ways, for example, as 22667121 + 5550736 = 4761^2 + 2356^2 .

It is a cyclic number.

It is not a de Polignac number, because 28217857 - 2⁷ = 28217729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28217851) 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, 81382 + ... + 81727.

It is an arithmetic number, because the mean of its divisors is an integer number (7095285).

Almost surely, 2^28217857 is an apocalyptic number.

It is an amenable number.

28217857 is a deficient number, since it is larger than the sum of its proper divisors (163283).

28217857 is a wasteful number, since it uses less digits than its factorization.

28217857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163282.

The product of its digits is 62720, while the sum is 40.

The square root of 28217857 is about 5312.0482866781. The cubic root of 28217857 is about 304.4444136263. Note that the first 4 decimals are identical.

The spelling of 28217857 in words is "twenty-eight million, two hundred seventeen thousand, eight hundred fifty-seven".