21204413 has 4 divisors (see below), whose sum is σ = 22126368. Its totient is φ = 20282460.

The previous prime is 21204397. The next prime is 21204419. The reversal of 21204413 is 31440212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21204413 - 2⁴ = 21204397 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21204391 and 21204400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204419) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 460943 + ... + 460988.

It is an arithmetic number, because the mean of its divisors is an integer number (5531592).

Almost surely, 2^21204413 is an apocalyptic number.

21204413 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21204413 is a deficient number, since it is larger than the sum of its proper divisors (921955).

21204413 is an equidigital number, since it uses as much as digits as its factorization.

21204413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 921954.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21204413 is about 4604.8249695292. The cubic root of 21204413 is about 276.7847032669.

Adding to 21204413 its reverse (31440212), we get a palindrome (52644625).

It can be divided in two parts, 212044 and 13, that multiplied together give a palindrome (2756572).

The spelling of 21204413 in words is "twenty-one million, two hundred four thousand, four hundred thirteen".