21128229 has 32 divisors (see below), whose sum is σ = 33454080. Its totient is φ = 13132800.

The previous prime is 21128213. The next prime is 21128257. The reversal of 21128229 is 92282112.

It is not a de Polignac number, because 21128229 - 2⁴ = 21128213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128279) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 87549 + ... + 87789.

It is an arithmetic number, because the mean of its divisors is an integer number (1045440).

Almost surely, 2^21128229 is an apocalyptic number.

It is an amenable number.

21128229 is a deficient number, since it is larger than the sum of its proper divisors (12325851).

21128229 is a wasteful number, since it uses less digits than its factorization.

21128229 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 458 (or 452 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 21128229 is about 4596.5453331823. The cubic root of 21128229 is about 276.4528247111.

The spelling of 21128229 in words is "twenty-one million, one hundred twenty-eight thousand, two hundred twenty-nine".