28021783 has 4 divisors (see below), whose sum is σ = 28416528. Its totient is φ = 27627040.

The previous prime is 28021781. The next prime is 28021813. The reversal of 28021783 is 38712082.

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 28021783 - 2¹ = 28021781 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 (28021781) 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 3 ways as a sum of consecutive naturals, for example, 197266 + ... + 197407.

It is an arithmetic number, because the mean of its divisors is an integer number (7104132).

Almost surely, 2^28021783 is an apocalyptic number.

28021783 is a deficient number, since it is larger than the sum of its proper divisors (394745).

28021783 is an equidigital number, since it uses as much as digits as its factorization.

28021783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394744.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 28021783 is about 5293.5605219927. The cubic root of 28021783 is about 303.7376220351.

The spelling of 28021783 in words is "twenty-eight million, twenty-one thousand, seven hundred eighty-three".