21301213 has 4 divisors (see below), whose sum is σ = 21312928. Its totient is φ = 21289500.

The previous prime is 21301201. The next prime is 21301219. The reversal of 21301213 is 31210312.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21301213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21301193 and 21301202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21301219) 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, 2481 + ... + 6982.

It is an arithmetic number, because the mean of its divisors is an integer number (5328232).

Almost surely, 2^21301213 is an apocalyptic number.

It is an amenable number.

21301213 is a deficient number, since it is larger than the sum of its proper divisors (11715).

21301213 is an equidigital number, since it uses as much as digits as its factorization.

21301213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11714.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21301213 is about 4615.3237156239. The cubic root of 21301213 is about 277.2052461029.

Adding to 21301213 its reverse (31210312), we get a palindrome (52511525).

Subtracting 21301213 from its reverse (31210312), we obtain a palindrome (9909099).

The spelling of 21301213 in words is "twenty-one million, three hundred one thousand, two hundred thirteen".