21304206 has 96 divisors (see below), whose sum is σ = 60652800. Its totient is φ = 5235840.

The previous prime is 21304147. The next prime is 21304219. The reversal of 21304206 is 60240312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 25930 + ... + 26738.

It is an arithmetic number, because the mean of its divisors is an integer number (631800).

Almost surely, 2^21304206 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21304206, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30326400).

21304206 is an abundant number, since it is smaller than the sum of its proper divisors (39348594).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21304206 is a wasteful number, since it uses less digits than its factorization.

21304206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 854 (or 851 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21304206 is about 4615.6479501799. The cubic root of 21304206 is about 277.2182287195.

Adding to 21304206 its reverse (60240312), we get a palindrome (81544518).

It can be divided in two parts, 2130 and 4206, that added together give a palindrome (6336).

The spelling of 21304206 in words is "twenty-one million, three hundred four thousand, two hundred six".