28317821 has 8 divisors (see below), whose sum is σ = 32416704. Its totient is φ = 24232320.

The previous prime is 28317803. The next prime is 28317823. The reversal of 28317821 is 12871382.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28317821 - 2¹⁴ = 28301437 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28317823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1706 + ... + 7716.

It is an arithmetic number, because the mean of its divisors is an integer number (4052088).

Almost surely, 2^28317821 is an apocalyptic number.

It is an amenable number.

28317821 is a deficient number, since it is larger than the sum of its proper divisors (4098883).

28317821 is an equidigital number, since it uses as much as digits as its factorization.

28317821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6691.

The product of its digits is 5376, while the sum is 32.

The square root of 28317821 is about 5321.4491447349. The cubic root of 28317821 is about 304.8034961067.

It can be divided in two parts, 28 and 317821, that multiplied together give a palindrome (8898988).

The spelling of 28317821 in words is "twenty-eight million, three hundred seventeen thousand, eight hundred twenty-one".