21214221 has 8 divisors (see below), whose sum is σ = 32326464. Its totient is φ = 12122400.

The previous prime is 21214187. The next prime is 21214229. The reversal of 21214221 is 12241212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21214221 - 2¹⁴ = 21197837 is a prime.

It is a Smith number, since the sum of its digits (15) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21214221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21214229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 505080 + ... + 505121.

It is an arithmetic number, because the mean of its divisors is an integer number (4040808).

Almost surely, 2^21214221 is an apocalyptic number.

21214221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21214221 is a deficient number, since it is larger than the sum of its proper divisors (11112243).

21214221 is a wasteful number, since it uses less digits than its factorization.

21214221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1010211.

The product of its digits is 64, while the sum is 15.

The square root of 21214221 is about 4605.8898163113. The cubic root of 21214221 is about 276.8273718366.

Adding to 21214221 its reverse (12241212), we get a palindrome (33455433).

It can be divided in two parts, 21 and 214221, that multiplied together give a square (4498641 = 2121²).

The spelling of 21214221 in words is "twenty-one million, two hundred fourteen thousand, two hundred twenty-one".