21313543 has 2 divisors, whose sum is σ = 21313544. Its totient is φ = 21313542.

The previous prime is 21313541. The next prime is 21313547. The reversal of 21313543 is 34531312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21313543 - 2¹ = 21313541 is a prime.

Together with 21313541, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21313541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656771 + 10656772.

It is an arithmetic number, because the mean of its divisors is an integer number (10656772).

Almost surely, 2^21313543 is an apocalyptic number.

21313543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21313543 is an equidigital number, since it uses as much as digits as its factorization.

21313543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1080, while the sum is 22.

The square root of 21313543 is about 4616.6592900061. The cubic root of 21313543 is about 277.2587216399.

Adding to 21313543 its reverse (34531312), we get a palindrome (55844855).

The spelling of 21313543 in words is "twenty-one million, three hundred thirteen thousand, five hundred forty-three".