20921773 has 2 divisors, whose sum is σ = 20921774. Its totient is φ = 20921772.

The previous prime is 20921741. The next prime is 20921777. The reversal of 20921773 is 37712902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20593444 + 328329 = 4538^2 + 573^2 .

It is a cyclic number.

It is not a de Polignac number, because 20921773 - 2⁵ = 20921741 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20921777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10460886 + 10460887.

It is an arithmetic number, because the mean of its divisors is an integer number (10460887).

Almost surely, 2^20921773 is an apocalyptic number.

It is an amenable number.

20921773 is a deficient number, since it is larger than the sum of its proper divisors (1).

20921773 is an equidigital number, since it uses as much as digits as its factorization.

20921773 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5292, while the sum is 31.

The square root of 20921773 is about 4574.0324659976. The cubic root of 20921773 is about 275.5494162035.

The spelling of 20921773 in words is "twenty million, nine hundred twenty-one thousand, seven hundred seventy-three".