20704561 has 2 divisors, whose sum is σ = 20704562. Its totient is φ = 20704560.

The previous prime is 20704529. The next prime is 20704573. The reversal of 20704561 is 16540702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16000000 + 4704561 = 4000^2 + 2169^2 .

It is a cyclic number.

It is not a de Polignac number, because 20704561 - 2⁵ = 20704529 is a prime.

It is not a weakly prime, because it can be changed into another prime (20704501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10352280 + 10352281.

It is an arithmetic number, because the mean of its divisors is an integer number (10352281).

Almost surely, 2^20704561 is an apocalyptic number.

It is an amenable number.

20704561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20704561 is an equidigital number, since it uses as much as digits as its factorization.

20704561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 20704561 is about 4550.2264778800. The cubic root of 20704561 is about 274.5925028017.

The spelling of 20704561 in words is "twenty million, seven hundred four thousand, five hundred sixty-one".