20947021 has 2 divisors, whose sum is σ = 20947022. Its totient is φ = 20947020.

The previous prime is 20947001. The next prime is 20947027. The reversal of 20947021 is 12074902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15721225 + 5225796 = 3965^2 + 2286^2 .

It is a cyclic number.

It is not a de Polignac number, because 20947021 - 2¹⁹ = 20422733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20947027) 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, 10473510 + 10473511.

It is an arithmetic number, because the mean of its divisors is an integer number (10473511).

Almost surely, 2^20947021 is an apocalyptic number.

It is an amenable number.

20947021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20947021 is an equidigital number, since it uses as much as digits as its factorization.

20947021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 20947021 is about 4576.7915617821. The cubic root of 20947021 is about 275.6602142539.

The spelling of 20947021 in words is "twenty million, nine hundred forty-seven thousand, twenty-one".