20873821 has 2 divisors, whose sum is σ = 20873822. Its totient is φ = 20873820.

The previous prime is 20873813. The next prime is 20873843. The reversal of 20873821 is 12837802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20839225 + 34596 = 4565^2 + 186^2 .

It is a cyclic number.

It is not a de Polignac number, because 20873821 - 2³ = 20873813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20873861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10436910 + 10436911.

It is an arithmetic number, because the mean of its divisors is an integer number (10436911).

Almost surely, 2^20873821 is an apocalyptic number.

It is an amenable number.

20873821 is a deficient number, since it is larger than the sum of its proper divisors (1).

20873821 is an equidigital number, since it uses as much as digits as its factorization.

20873821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 20873821 is about 4568.7876947829. The cubic root of 20873821 is about 275.3387385015.

The spelling of 20873821 in words is "twenty million, eight hundred seventy-three thousand, eight hundred twenty-one".