21229217 has 4 divisors (see below), whose sum is σ = 21255360. Its totient is φ = 21203076.

The previous prime is 21229199. The next prime is 21229237. The reversal of 21229217 is 71292212.

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 21229217 - 2¹² = 21225121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21229237) 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, 11813 + ... + 13490.

It is an arithmetic number, because the mean of its divisors is an integer number (5313840).

Almost surely, 2^21229217 is an apocalyptic number.

It is an amenable number.

21229217 is a deficient number, since it is larger than the sum of its proper divisors (26143).

21229217 is an equidigital number, since it uses as much as digits as its factorization.

21229217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26142.

The product of its digits is 1008, while the sum is 26.

The square root of 21229217 is about 4607.5174443511. The cubic root of 21229217 is about 276.8925847817.

The spelling of 21229217 in words is "twenty-one million, two hundred twenty-nine thousand, two hundred seventeen".