21168313 has 2 divisors, whose sum is σ = 21168314. Its totient is φ = 21168312.

The previous prime is 21168311. The next prime is 21168331. The reversal of 21168313 is 31386112.

Together with next prime (21168331) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20142144 + 1026169 = 4488^2 + 1013^2 .

It is a cyclic number.

It is not a de Polignac number, because 21168313 - 2¹ = 21168311 is a prime.

Together with 21168311, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21168311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10584156 + 10584157.

It is an arithmetic number, because the mean of its divisors is an integer number (10584157).

Almost surely, 2^21168313 is an apocalyptic number.

It is an amenable number.

21168313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21168313 is an equidigital number, since it uses as much as digits as its factorization.

21168313 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 25.

The square root of 21168313 is about 4600.9034982273. The cubic root of 21168313 is about 276.6275409584.

The spelling of 21168313 in words is "twenty-one million, one hundred sixty-eight thousand, three hundred thirteen".