21313305 has 24 divisors (see below), whose sum is σ = 39785928. Its totient is φ = 10492416.

The previous prime is 21313301. The next prime is 21313333. The reversal of 21313305 is 50331312.

It can be written as a sum of positive squares in 4 ways, for example, as 2442969 + 18870336 = 1563^2 + 4344^2 .

It is not a de Polignac number, because 21313305 - 2² = 21313301 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21313301) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17632 + ... + 18801.

It is an arithmetic number, because the mean of its divisors is an integer number (1657747).

Almost surely, 2^21313305 is an apocalyptic number.

It is an amenable number.

21313305 is a deficient number, since it is larger than the sum of its proper divisors (18472623).

21313305 is a wasteful number, since it uses less digits than its factorization.

21313305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36457 (or 36454 counting only the distinct ones).

The product of its (nonzero) digits is 270, while the sum is 18.

The square root of 21313305 is about 4616.6335137197. The cubic root of 21313305 is about 277.2576896228.

Adding to 21313305 its reverse (50331312), we get a palindrome (71644617).

The spelling of 21313305 in words is "twenty-one million, three hundred thirteen thousand, three hundred five".