20821349 has 2 divisors, whose sum is σ = 20821350. Its totient is φ = 20821348.

The previous prime is 20821327. The next prime is 20821351. The reversal of 20821349 is 94312802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17556100 + 3265249 = 4190^2 + 1807^2 .

It is a cyclic number.

It is not a de Polignac number, because 20821349 - 2¹² = 20817253 is a prime.

Together with 20821351, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20821309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10410674 + 10410675.

It is an arithmetic number, because the mean of its divisors is an integer number (10410675).

Almost surely, 2^20821349 is an apocalyptic number.

It is an amenable number.

20821349 is a deficient number, since it is larger than the sum of its proper divisors (1).

20821349 is an equidigital number, since it uses as much as digits as its factorization.

20821349 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 20821349 is about 4563.0416390824. The cubic root of 20821349 is about 275.1078320919.

The spelling of 20821349 in words is "twenty million, eight hundred twenty-one thousand, three hundred forty-nine".