21606229 has 6 divisors (see below), whose sum is σ = 22077974. Its totient is φ = 21144360.

The previous prime is 21606217. The next prime is 21606259. The reversal of 21606229 is 92260612.

It can be written as a sum of positive squares in only one way, i.e., 17892900 + 3713329 = 4230^2 + 1927^2 .

It is not a de Polignac number, because 21606229 - 2¹¹ = 21604181 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21606197 and 21606206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21606259) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2682 + ... + 7099.

Almost surely, 2^21606229 is an apocalyptic number.

It is an amenable number.

21606229 is a deficient number, since it is larger than the sum of its proper divisors (471745).

21606229 is an frugal number, since it uses more digits than its factorization.

21606229 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9875 (or 9828 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 21606229 is about 4648.2501008444. The cubic root of 21606229 is about 278.5220982372.

The spelling of 21606229 in words is "twenty-one million, six hundred six thousand, two hundred twenty-nine".