20917229 has 2 divisors, whose sum is σ = 20917230. Its totient is φ = 20917228.

The previous prime is 20917223. The next prime is 20917241. The reversal of 20917229 is 92271902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20912329 + 4900 = 4573^2 + 70^2 .

It is a cyclic number.

It is not a de Polignac number, because 20917229 - 2¹² = 20913133 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20917195 and 20917204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20917223) 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, 10458614 + 10458615.

It is an arithmetic number, because the mean of its divisors is an integer number (10458615).

Almost surely, 2^20917229 is an apocalyptic number.

It is an amenable number.

20917229 is a deficient number, since it is larger than the sum of its proper divisors (1).

20917229 is an equidigital number, since it uses as much as digits as its factorization.

20917229 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 20917229 is about 4573.5357219552. The cubic root of 20917229 is about 275.5294658993.

The spelling of 20917229 in words is "twenty million, nine hundred seventeen thousand, two hundred twenty-nine".