20821841 has 2 divisors, whose sum is σ = 20821842. Its totient is φ = 20821840.

The previous prime is 20821789. The next prime is 20821849. The reversal of 20821841 is 14812802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13719616 + 7102225 = 3704^2 + 2665^2 .

It is a cyclic number.

It is not a de Polignac number, because 20821841 - 2¹⁰ = 20820817 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20821841.

It is not a weakly prime, because it can be changed into another prime (20821849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10410920 + 10410921.

It is an arithmetic number, because the mean of its divisors is an integer number (10410921).

Almost surely, 2^20821841 is an apocalyptic number.

It is an amenable number.

20821841 is a deficient number, since it is larger than the sum of its proper divisors (1).

20821841 is an equidigital number, since it uses as much as digits as its factorization.

20821841 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 20821841 is about 4563.0955501721. The cubic root of 20821841 is about 275.1099989702.

The spelling of 20821841 in words is "twenty million, eight hundred twenty-one thousand, eight hundred forty-one".