21456313 has 2 divisors, whose sum is σ = 21456314. Its totient is φ = 21456312.

The previous prime is 21456311. The next prime is 21456319. The reversal of 21456313 is 31365412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15657849 + 5798464 = 3957^2 + 2408^2 .

It is a cyclic number.

It is not a de Polignac number, because 21456313 - 2¹ = 21456311 is a prime.

Together with 21456311, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21456311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10728156 + 10728157.

It is an arithmetic number, because the mean of its divisors is an integer number (10728157).

Almost surely, 2^21456313 is an apocalyptic number.

It is an amenable number.

21456313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21456313 is an equidigital number, since it uses as much as digits as its factorization.

21456313 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 25.

The square root of 21456313 is about 4632.0959618730. The cubic root of 21456313 is about 277.8764223104.

Subtracting 21456313 from its reverse (31365412), we obtain a palindrome (9909099).

The spelling of 21456313 in words is "twenty-one million, four hundred fifty-six thousand, three hundred thirteen".