28724239 has 8 divisors (see below), whose sum is σ = 29945520. Its totient is φ = 27518400.

The previous prime is 28724233. The next prime is 28724279. The reversal of 28724239 is 93242782.

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 28724239 - 2⁵ = 28724207 is a prime.

It is a super-2 number, since 2×28724239² = 1650163812258242, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28724198 and 28724207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28724233) 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, 19 + ... + 7579.

It is an arithmetic number, because the mean of its divisors is an integer number (3743190).

Almost surely, 2^28724239 is an apocalyptic number.

28724239 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

28724239 is a deficient number, since it is larger than the sum of its proper divisors (1221281).

28724239 is a wasteful number, since it uses less digits than its factorization.

28724239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7721.

The product of its digits is 48384, while the sum is 37.

The square root of 28724239 is about 5359.4998833846. The cubic root of 28724239 is about 306.2547574438.

The spelling of 28724239 in words is "twenty-eight million, seven hundred twenty-four thousand, two hundred thirty-nine".