21403213 has 8 divisors (see below), whose sum is σ = 23279256. Its totient is φ = 19560000.

The previous prime is 21403211. The next prime is 21403229. The reversal of 21403213 is 31230412.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 8421604 + 12981609 = 2902^2 + 3603^2 .

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 21403213 - 2¹ = 21403211 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21403211) 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, 6838 + ... + 9463.

It is an arithmetic number, because the mean of its divisors is an integer number (2909907).

Almost surely, 2^21403213 is an apocalyptic number.

It is an amenable number.

21403213 is a deficient number, since it is larger than the sum of its proper divisors (1876043).

21403213 is a wasteful number, since it uses less digits than its factorization.

21403213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16415.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21403213 is about 4626.3606647126. The cubic root of 21403213 is about 277.6470037882.

Adding to 21403213 its reverse (31230412), we get a palindrome (52633625).

The spelling of 21403213 in words is "twenty-one million, four hundred three thousand, two hundred thirteen".