21224471 has 4 divisors (see below), whose sum is σ = 21319872. Its totient is φ = 21129072.

The previous prime is 21224447. The next prime is 21224479. The reversal of 21224471 is 17442212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21224471 - 2¹⁴ = 21208087 is a prime.

It is a super-3 number, since 3×21224471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224479) 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, 47366 + ... + 47811.

It is an arithmetic number, because the mean of its divisors is an integer number (5329968).

Almost surely, 2^21224471 is an apocalyptic number.

21224471 is a deficient number, since it is larger than the sum of its proper divisors (95401).

21224471 is an equidigital number, since it uses as much as digits as its factorization.

21224471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95400.

The product of its digits is 896, while the sum is 23.

The square root of 21224471 is about 4607.0023876703. The cubic root of 21224471 is about 276.8719492247.

Adding to 21224471 its reverse (17442212), we get a palindrome (38666683).

The spelling of 21224471 in words is "twenty-one million, two hundred twenty-four thousand, four hundred seventy-one".