20217749 has 2 divisors, whose sum is σ = 20217750. Its totient is φ = 20217748.

The previous prime is 20217733. The next prime is 20217761. The reversal of 20217749 is 94771202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14577124 + 5640625 = 3818^2 + 2375^2 .

It is a cyclic number.

It is not a de Polignac number, because 20217749 - 2⁴ = 20217733 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20217949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10108874 + 10108875.

It is an arithmetic number, because the mean of its divisors is an integer number (10108875).

Almost surely, 2^20217749 is an apocalyptic number.

It is an amenable number.

20217749 is a deficient number, since it is larger than the sum of its proper divisors (1).

20217749 is an equidigital number, since it uses as much as digits as its factorization.

20217749 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 20217749 is about 4496.4151276322. The cubic root of 20217749 is about 272.4233109112.

The spelling of 20217749 in words is "twenty million, two hundred seventeen thousand, seven hundred forty-nine".