28139309 has 8 divisors (see below), whose sum is σ = 31756320. Its totient is φ = 24698800.

The previous prime is 28139297. The next prime is 28139311. The reversal of 28139309 is 90393182.

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

It is a cyclic number.

It is not a de Polignac number, because 28139309 - 2⁸ = 28139053 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 (28139339) 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, 43787 + ... + 44424.

It is an arithmetic number, because the mean of its divisors is an integer number (3969540).

Almost surely, 2^28139309 is an apocalyptic number.

28139309 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

28139309 is a deficient number, since it is larger than the sum of its proper divisors (3617011).

28139309 is a wasteful number, since it uses less digits than its factorization.

28139309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88251.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 28139309 is about 5304.6497528112. The cubic root of 28139309 is about 304.1616645035.

The spelling of 28139309 in words is "twenty-eight million, one hundred thirty-nine thousand, three hundred nine".