21313566 has 24 divisors (see below), whose sum is σ = 46298304. Its totient is φ = 7086240.

The previous prime is 21313547. The next prime is 21313577. The reversal of 21313566 is 66531312.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6931 + ... + 9521.

It is an arithmetic number, because the mean of its divisors is an integer number (1929096).

Almost surely, 2^21313566 is an apocalyptic number.

21313566 is an abundant number, since it is smaller than the sum of its proper divisors (24984738).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21313566 is a wasteful number, since it uses less digits than its factorization.

21313566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3056 (or 3053 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 21313566 is about 4616.6617809842. The cubic root of 21313566 is about 277.2588213723.

Adding to 21313566 its reverse (66531312), we get a palindrome (87844878).

The spelling of 21313566 in words is "twenty-one million, three hundred thirteen thousand, five hundred sixty-six".