21169 has 2 divisors, whose sum is σ = 21170. Its totient is φ = 21168.

The previous prime is 21163. The next prime is 21179. The reversal of 21169 is 96112.

21169 is nontrivially palindromic in base 12.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21025 + 144 = 145^2 + 12^2 .

It is a cyclic number.

It is not a de Polignac number, because 21169 - 2¹¹ = 19121 is a prime.

It is a super-2 number, since 2×21169² = 896253122, which contains 22 as substring.

It is a Chen prime.

21169 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (21163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10584 + 10585.

It is an arithmetic number, because the mean of its divisors is an integer number (10585).

2²¹¹⁶⁹ is an apocalyptic number.

It is an amenable number.

21169 is a deficient number, since it is larger than the sum of its proper divisors (1).

21169 is an equidigital number, since it uses as much as digits as its factorization.

21169 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108, while the sum is 19.

The square root of 21169 is about 145.4957044039. The cubic root of 21169 is about 27.6630533498.

It can be divided in two parts, 2116 and 9, that multiplied together give a square (19044 = 138²).

The spelling of 21169 in words is "twenty-one thousand, one hundred sixty-nine".