21000229 has 2 divisors, whose sum is σ = 21000230. Its totient is φ = 21000228.

The previous prime is 21000193. The next prime is 21000233. The reversal of 21000229 is 92200012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14250625 + 6749604 = 3775^2 + 2598^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000229 - 2¹⁷ = 20869157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500114 + 10500115.

It is an arithmetic number, because the mean of its divisors is an integer number (10500115).

Almost surely, 2^21000229 is an apocalyptic number.

It is an amenable number.

21000229 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000229 is an equidigital number, since it uses as much as digits as its factorization.

21000229 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21000229 is about 4582.6006808362. The cubic root of 21000229 is about 275.8934204815.

The spelling of 21000229 in words is "twenty-one million, two hundred twenty-nine", and thus it is an aban number.