28928639 has 4 divisors (see below), whose sum is σ = 28939440. Its totient is φ = 28917840.

The previous prime is 28928633. The next prime is 28928651. The reversal of 28928639 is 93682982.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28928639 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28928593 and 28928602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28928633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1979 + ... + 7859.

It is an arithmetic number, because the mean of its divisors is an integer number (7234860).

Almost surely, 2^28928639 is an apocalyptic number.

28928639 is a deficient number, since it is larger than the sum of its proper divisors (10801).

28928639 is an equidigital number, since it uses as much as digits as its factorization.

28928639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10800.

The product of its digits is 373248, while the sum is 47.

The square root of 28928639 is about 5378.5350235915. The cubic root of 28928639 is about 306.9794714422.

The spelling of 28928639 in words is "twenty-eight million, nine hundred twenty-eight thousand, six hundred thirty-nine".