28304639 has 4 divisors (see below), whose sum is σ = 30877800. Its totient is φ = 25731480.

The previous prime is 28304569. The next prime is 28304641. The reversal of 28304639 is 93640382.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28304639 - 2¹² = 28300543 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28304599 and 28304608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28304659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1286564 + ... + 1286585.

It is an arithmetic number, because the mean of its divisors is an integer number (7719450).

Almost surely, 2^28304639 is an apocalyptic number.

28304639 is a deficient number, since it is larger than the sum of its proper divisors (2573161).

28304639 is a wasteful number, since it uses less digits than its factorization.

28304639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2573160.

The product of its (nonzero) digits is 31104, while the sum is 35.

The square root of 28304639 is about 5320.2104281692. The cubic root of 28304639 is about 304.7561932287.

The spelling of 28304639 in words is "twenty-eight million, three hundred four thousand, six hundred thirty-nine".