20705261 has 2 divisors, whose sum is σ = 20705262. Its totient is φ = 20705260.

The previous prime is 20705203. The next prime is 20705273. The reversal of 20705261 is 16250702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12208036 + 8497225 = 3494^2 + 2915^2 .

It is a cyclic number.

It is not a de Polignac number, because 20705261 - 2⁶ = 20705197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20705281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10352630 + 10352631.

It is an arithmetic number, because the mean of its divisors is an integer number (10352631).

Almost surely, 2^20705261 is an apocalyptic number.

It is an amenable number.

20705261 is a deficient number, since it is larger than the sum of its proper divisors (1).

20705261 is an equidigital number, since it uses as much as digits as its factorization.

20705261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 20705261 is about 4550.3033964781. The cubic root of 20705261 is about 274.5955973306.

Adding to 20705261 its reverse (16250702), we get a palindrome (36955963).

The spelling of 20705261 in words is "twenty million, seven hundred five thousand, two hundred sixty-one".