28979521 has 4 divisors (see below), whose sum is σ = 29007700. Its totient is φ = 28951344.

The previous prime is 28979507. The next prime is 28979537. The reversal of 28979521 is 12597982.

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

It can be written as a sum of positive squares in 2 ways, for example, as 11128896 + 17850625 = 3336^2 + 4225^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28979521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28979551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12486 + ... + 14623.

It is an arithmetic number, because the mean of its divisors is an integer number (7251925).

Almost surely, 2^28979521 is an apocalyptic number.

It is an amenable number.

28979521 is a deficient number, since it is larger than the sum of its proper divisors (28179).

28979521 is a wasteful number, since it uses less digits than its factorization.

28979521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28178.

The product of its digits is 90720, while the sum is 43.

The square root of 28979521 is about 5383.2630439168. The cubic root of 28979521 is about 307.1593460256.

The spelling of 28979521 in words is "twenty-eight million, nine hundred seventy-nine thousand, five hundred twenty-one".