21228229 has 4 divisors (see below), whose sum is σ = 23158080. Its totient is φ = 19298380.

The previous prime is 21228227. The next prime is 21228247. The reversal of 21228229 is 92282212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21228229 - 2¹ = 21228227 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21228197 and 21228206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 964909 + ... + 964930.

It is an arithmetic number, because the mean of its divisors is an integer number (5789520).

Almost surely, 2^21228229 is an apocalyptic number.

It is an amenable number.

21228229 is a deficient number, since it is larger than the sum of its proper divisors (1929851).

21228229 is a wasteful number, since it uses less digits than its factorization.

21228229 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1929850.

The product of its digits is 2304, while the sum is 28.

The square root of 21228229 is about 4607.4102270147. The cubic root of 21228229 is about 276.8882892218. Note that the first 3 decimals are identical.

It can be divided in two parts, 212 and 28229, that added together give a triangular number (28441 = T₂₃₈).

The spelling of 21228229 in words is "twenty-one million, two hundred twenty-eight thousand, two hundred twenty-nine".