21231313 has 2 divisors, whose sum is σ = 21231314. Its totient is φ = 21231312.

The previous prime is 21231307. The next prime is 21231359. The reversal of 21231313 is 31313212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12159169 + 9072144 = 3487^2 + 3012^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231313 - 2⁹ = 21230801 is a prime.

It is not a weakly prime, because it can be changed into another prime (21231713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615656 + 10615657.

It is an arithmetic number, because the mean of its divisors is an integer number (10615657).

Almost surely, 2^21231313 is an apocalyptic number.

It is an amenable number.

21231313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231313 is an equidigital number, since it uses as much as digits as its factorization.

21231313 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108, while the sum is 16.

The square root of 21231313 is about 4607.7448931120. The cubic root of 21231313 is about 276.9016971881.

Adding to 21231313 its reverse (31313212), we get a palindrome (52544525).

The spelling of 21231313 in words is "twenty-one million, two hundred thirty-one thousand, three hundred thirteen".