21420223 has 8 divisors (see below), whose sum is σ = 23587200. Its totient is φ = 19289880.

The previous prime is 21420209. The next prime is 21420227. The reversal of 21420223 is 32202412.

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

It is a cyclic number.

It is not a de Polignac number, because 21420223 - 2²¹ = 19323071 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21420197 and 21420206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7923 + ... + 10276.

It is an arithmetic number, because the mean of its divisors is an integer number (2948400).

Almost surely, 2^21420223 is an apocalyptic number.

21420223 is a deficient number, since it is larger than the sum of its proper divisors (2166977).

21420223 is a wasteful number, since it uses less digits than its factorization.

21420223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18317.

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21420223 is about 4628.1986776715. The cubic root of 21420223 is about 277.7205367505.

Adding to 21420223 its reverse (32202412), we get a palindrome (53622635).

The spelling of 21420223 in words is "twenty-one million, four hundred twenty thousand, two hundred twenty-three".