28521857 has 32 divisors (see below), whose sum is σ = 37078272. Its totient is φ = 21337344.

The previous prime is 28521853. The next prime is 28521881. The reversal of 28521857 is 75812582.

It is a happy number.

It is not a de Polignac number, because 28521857 - 2² = 28521853 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28521857.

It is not an unprimeable number, because it can be changed into a prime (28521851) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 144683 + ... + 144879.

It is an arithmetic number, because the mean of its divisors is an integer number (1158696).

Almost surely, 2^28521857 is an apocalyptic number.

It is an amenable number.

28521857 is a deficient number, since it is larger than the sum of its proper divisors (8556415).

28521857 is a wasteful number, since it uses less digits than its factorization.

28521857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297.

The product of its digits is 44800, while the sum is 38.

The square root of 28521857 is about 5340.5858292888. The cubic root of 28521857 is about 305.5338031800.

The spelling of 28521857 in words is "twenty-eight million, five hundred twenty-one thousand, eight hundred fifty-seven".