20421229 has 2 divisors, whose sum is σ = 20421230. Its totient is φ = 20421228.

The previous prime is 20421227. The next prime is 20421241. The reversal of 20421229 is 92212402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20232004 + 189225 = 4498^2 + 435^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421229 - 2¹ = 20421227 is a prime.

Together with 20421227, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20421223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210614 + 10210615.

It is an arithmetic number, because the mean of its divisors is an integer number (10210615).

Almost surely, 2^20421229 is an apocalyptic number.

It is an amenable number.

20421229 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421229 is an equidigital number, since it uses as much as digits as its factorization.

20421229 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 20421229 is about 4518.9853949753. The cubic root of 20421229 is about 273.3341897984.

The spelling of 20421229 in words is "twenty million, four hundred twenty-one thousand, two hundred twenty-nine".