28139815 has 8 divisors (see below), whose sum is σ = 36837648. Its totient is φ = 20465280.

The previous prime is 28139807. The next prime is 28139819. The reversal of 28139815 is 51893182.

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

It is not a de Polignac number, because 28139815 - 2³ = 28139807 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 (28139819) 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, 255762 + ... + 255871.

It is an arithmetic number, because the mean of its divisors is an integer number (4604706).

Almost surely, 2^28139815 is an apocalyptic number.

28139815 is a deficient number, since it is larger than the sum of its proper divisors (8697833).

28139815 is a wasteful number, since it uses less digits than its factorization.

28139815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 511649.

The product of its digits is 17280, while the sum is 37.

The square root of 28139815 is about 5304.6974466033. The cubic root of 28139815 is about 304.1634876338.

The spelling of 28139815 in words is "twenty-eight million, one hundred thirty-nine thousand, eight hundred fifteen".