21312313 has 8 divisors (see below), whose sum is σ = 23481216. Its totient is φ = 19182000.

The previous prime is 21312299. The next prime is 21312323. The reversal of 21312313 is 31321312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21312313 - 2¹³ = 21304121 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21312323) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8481 + ... + 10702.

It is an arithmetic number, because the mean of its divisors is an integer number (2935152).

Almost surely, 2^21312313 is an apocalyptic number.

It is an amenable number.

21312313 is a deficient number, since it is larger than the sum of its proper divisors (2168903).

21312313 is a wasteful number, since it uses less digits than its factorization.

21312313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19295.

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

The square root of 21312313 is about 4616.5260748749. The cubic root of 21312313 is about 277.2533880235.

Adding to 21312313 its reverse (31321312), we get a palindrome (52633625).

It can be divided in two parts, 2131 and 2313, that added together give a palindrome (4444).

The spelling of 21312313 in words is "twenty-one million, three hundred twelve thousand, three hundred thirteen".