20817229 has 2 divisors, whose sum is σ = 20817230. Its totient is φ = 20817228.

The previous prime is 20817221. The next prime is 20817233. The reversal of 20817229 is 92271802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20232004 + 585225 = 4498^2 + 765^2 .

It is a cyclic number.

It is not a de Polignac number, because 20817229 - 2³ = 20817221 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20817229.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20817221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10408614 + 10408615.

It is an arithmetic number, because the mean of its divisors is an integer number (10408615).

Almost surely, 2^20817229 is an apocalyptic number.

It is an amenable number.

20817229 is a deficient number, since it is larger than the sum of its proper divisors (1).

20817229 is an equidigital number, since it uses as much as digits as its factorization.

20817229 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 20817229 is about 4562.5901634927. The cubic root of 20817229 is about 275.0896853484.

The spelling of 20817229 in words is "twenty million, eight hundred seventeen thousand, two hundred twenty-nine".