28208521 has 16 divisors (see below), whose sum is σ = 32659200. Its totient is φ = 24094800.

The previous prime is 28208489. The next prime is 28208539. The reversal of 28208521 is 12580282.

28208521 = T₁₃₈ + T₁₃₉ + ... + T₅₅₅.

It is a cyclic number.

It is not a de Polignac number, because 28208521 - 2⁵ = 28208489 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 28208521.

It is not an unprimeable number, because it can be changed into a prime (28208581) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28566 + ... + 29536.

It is an arithmetic number, because the mean of its divisors is an integer number (2041200).

Almost surely, 2^28208521 is an apocalyptic number.

It is an amenable number.

28208521 is a deficient number, since it is larger than the sum of its proper divisors (4450679).

28208521 is a wasteful number, since it uses less digits than its factorization.

28208521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1140.

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 28208521 is about 5311.1694569087. The cubic root of 28208521 is about 304.4108343392.

The spelling of 28208521 in words is "twenty-eight million, two hundred eight thousand, five hundred twenty-one".