24821 has 2 divisors, whose sum is σ = 24822. Its totient is φ = 24820.

The previous prime is 24809. The next prime is 24841. The reversal of 24821 is 12842.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16900 + 7921 = 130^2 + 89^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-24821 is a prime.

It is a Chen prime.

It is a plaindrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 24821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (24841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12410 + 12411.

It is an arithmetic number, because the mean of its divisors is an integer number (12411).

2²⁴⁸²¹ is an apocalyptic number.

It is an amenable number.

24821 is a deficient number, since it is larger than the sum of its proper divisors (1).

24821 is an equidigital number, since it uses as much as digits as its factorization.

24821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 128, while the sum is 17.

The square root of 24821 is about 157.5468184382. The cubic root of 24821 is about 29.1702236025.

The spelling of 24821 in words is "twenty-four thousand, eight hundred twenty-one".