21396313 has 4 divisors (see below), whose sum is σ = 21405748. Its totient is φ = 21386880.

The previous prime is 21396289. The next prime is 21396317. The reversal of 21396313 is 31369312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 14197824 + 7198489 = 3768^2 + 2683^2 .

It is a cyclic number.

It is not a de Polignac number, because 21396313 - 2¹⁷ = 21265241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21396317) 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, 973 + ... + 6613.

It is an arithmetic number, because the mean of its divisors is an integer number (5351437).

It is a 2268-hyperperfect number.

Almost surely, 2^21396313 is an apocalyptic number.

It is an amenable number.

21396313 is a deficient number, since it is larger than the sum of its proper divisors (9435).

21396313 is an equidigital number, since it uses as much as digits as its factorization.

21396313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9434.

The product of its digits is 2916, while the sum is 28.

The square root of 21396313 is about 4625.6148780459. The cubic root of 21396313 is about 277.6171644952.

The spelling of 21396313 in words is "twenty-one million, three hundred ninety-six thousand, three hundred thirteen".