28878509 has 8 divisors (see below), whose sum is σ = 31570560. Its totient is φ = 26197600.

The previous prime is 28878497. The next prime is 28878517. The reversal of 28878509 is 90587882.

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

It is a de Polignac number, because none of the positive numbers 2^k-28878509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28878209) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3212 + ... + 8250.

It is an arithmetic number, because the mean of its divisors is an integer number (3946320).

Almost surely, 2^28878509 is an apocalyptic number.

It is an amenable number.

28878509 is a deficient number, since it is larger than the sum of its proper divisors (2692051).

28878509 is a wasteful number, since it uses less digits than its factorization.

28878509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5571.

The product of its (nonzero) digits is 322560, while the sum is 47.

The square root of 28878509 is about 5373.8728120416. The cubic root of 28878509 is about 306.8020488943.

The spelling of 28878509 in words is "twenty-eight million, eight hundred seventy-eight thousand, five hundred nine".