21404210 has 8 divisors (see below), whose sum is σ = 38527596. Its totient is φ = 8561680.

The previous prime is 21404183. The next prime is 21404213. The reversal of 21404210 is 1240412.

It can be written as a sum of positive squares in 2 ways, for example, as 17197609 + 4206601 = 4147^2 + 2051^2 .

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

It is a Curzon number.

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 (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1070201 + ... + 1070220.

Almost surely, 2^21404210 is an apocalyptic number.

21404210 is a deficient number, since it is larger than the sum of its proper divisors (17123386).

21404210 is a wasteful number, since it uses less digits than its factorization.

21404210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2140428.

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21404210 is about 4626.4684155412. The cubic root of 21404210 is about 277.6513148196.

Adding to 21404210 its reverse (1240412), we get a palindrome (22644622).

The spelling of 21404210 in words is "twenty-one million, four hundred four thousand, two hundred ten".