20717261 has 2 divisors, whose sum is σ = 20717262. Its totient is φ = 20717260.

The previous prime is 20717251. The next prime is 20717377. The reversal of 20717261 is 16271702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18541636 + 2175625 = 4306^2 + 1475^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20717261 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20717261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20717231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10358630 + 10358631.

It is an arithmetic number, because the mean of its divisors is an integer number (10358631).

Almost surely, 2^20717261 is an apocalyptic number.

It is an amenable number.

20717261 is a deficient number, since it is larger than the sum of its proper divisors (1).

20717261 is an equidigital number, since it uses as much as digits as its factorization.

20717261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1176, while the sum is 26.

The square root of 20717261 is about 4551.6217988756. The cubic root of 20717261 is about 274.6486355543.

Adding to 20717261 its reverse (16271702), we get a palindrome (36988963).

The spelling of 20717261 in words is "twenty million, seven hundred seventeen thousand, two hundred sixty-one".