21404219 has 4 divisors (see below), whose sum is σ = 21424896. Its totient is φ = 21383544.

The previous prime is 21404213. The next prime is 21404263. The reversal of 21404219 is 91240412.

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 21404219 - 2¹⁶ = 21338683 is a prime.

It is a super-2 number, since 2×21404219² = 916281181999922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21404194 and 21404203.

It is not an unprimeable number, because it can be changed into a prime (21404213) 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, 8699 + ... + 10884.

It is an arithmetic number, because the mean of its divisors is an integer number (5356224).

Almost surely, 2^21404219 is an apocalyptic number.

21404219 is a deficient number, since it is larger than the sum of its proper divisors (20677).

21404219 is a wasteful number, since it uses less digits than its factorization.

21404219 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20676.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21404219 is about 4626.4693882052. The cubic root of 21404219 is about 277.6513537350.

The spelling of 21404219 in words is "twenty-one million, four hundred four thousand, two hundred nineteen".