28921 has 2 divisors, whose sum is σ = 28922.
Its totient is φ = 28920.
The previous prime is 28909. The next prime is 28927. The reversal of 28921 is 12982.
28921 is nontrivially palindromic in base 5.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 26896 + 2025 = 164^2 + 45^2
It is a cyclic number.
It is not a de Polignac number, because 28921 - 27 = 28793 is a prime.
It is a pancake number, because a pancake can be divided into 28921 parts by 240 straight cuts.
28921 is a lucky number.
It is a nialpdrome in base 15.
It is a junction number, because it is equal to n+sod(n) for n = 28892 and 28901.
It is not a weakly prime, because it can be changed into another prime (28927) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14460 + 14461.
It is an arithmetic number, because the mean of its divisors is an integer number (14461).
228921 is an apocalyptic number.
It is an amenable number.
28921 is a deficient number, since it is larger than the sum of its proper divisors (1).
28921 is an equidigital number, since it uses as much as digits as its factorization.
28921 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 288, while the sum is 22.
The square root of 28921 is about 170.0617534897.
The cubic root of 28921 is about 30.6952448364.
The spelling of 28921 in words is "twenty-eight thousand, nine hundred twenty-one".