28439723 has 4 divisors (see below), whose sum is σ = 30627408. Its totient is φ = 26252040.

The previous prime is 28439669. The next prime is 28439731. The reversal of 28439723 is 32793482.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32793482 = 2 ⋅16396741.

It is a cyclic number.

It is not a de Polignac number, because 28439723 - 2⁶ = 28439659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28439743) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1093823 + ... + 1093848.

It is an arithmetic number, because the mean of its divisors is an integer number (7656852).

Almost surely, 2^28439723 is an apocalyptic number.

28439723 is a deficient number, since it is larger than the sum of its proper divisors (2187685).

28439723 is a wasteful number, since it uses less digits than its factorization.

28439723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2187684.

The product of its digits is 72576, while the sum is 38.

The square root of 28439723 is about 5332.8906795471. The cubic root of 28439723 is about 305.2402407108.

The spelling of 28439723 in words is "twenty-eight million, four hundred thirty-nine thousand, seven hundred twenty-three".