28915521 has 8 divisors (see below), whose sum is σ = 40821984. Its totient is φ = 18143040.

The previous prime is 28915517. The next prime is 28915559. The reversal of 28915521 is 12551982.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28915521 - 2² = 28915517 is a prime.

It is a super-2 number, since 2×28915521² = 1672214709402882, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28915561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 283435 + ... + 283536.

It is an arithmetic number, because the mean of its divisors is an integer number (5102748).

Almost surely, 2^28915521 is an apocalyptic number.

It is an amenable number.

28915521 is a deficient number, since it is larger than the sum of its proper divisors (11906463).

28915521 is a wasteful number, since it uses less digits than its factorization.

28915521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 566991.

The product of its digits is 7200, while the sum is 33.

The square root of 28915521 is about 5377.3154082683. The cubic root of 28915521 is about 306.9330633879.

The spelling of 28915521 in words is "twenty-eight million, nine hundred fifteen thousand, five hundred twenty-one".