20549 has 2 divisors, whose sum is σ = 20550. Its totient is φ = 20548.

The previous prime is 20543. The next prime is 20551. The reversal of 20549 is 94502.

20549 is nontrivially palindromic in base 8.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20449 + 100 = 143^2 + 10^2 .

It is a cyclic number.

It is not a de Polignac number, because 20549 - 2⁴ = 20533 is a prime.

It is a super-2 number, since 2×20549² = 844522802, which contains 22 as substring.

Together with 20551, it forms a pair of twin primes.

It is a Chen prime.

It is a nialpdrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 20549.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10274 + 10275.

It is an arithmetic number, because the mean of its divisors is an integer number (10275).

2²⁰⁵⁴⁹ is an apocalyptic number.

It is an amenable number.

20549 is a deficient number, since it is larger than the sum of its proper divisors (1).

20549 is an equidigital number, since it uses as much as digits as its factorization.

20549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 20549 is about 143.3492239253. The cubic root of 20549 is about 27.3903068347.

The spelling of 20549 in words is "twenty thousand, five hundred forty-nine".