21031317 has 12 divisors (see below), whose sum is σ = 30894240. Its totient is φ = 13782888.

The previous prime is 21031313. The next prime is 21031333. The reversal of 21031317 is 71313012.

It is not a de Polignac number, because 21031317 - 2² = 21031313 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21031317.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031313) by changing a digit.

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, 19273 + ... + 20334.

It is an arithmetic number, because the mean of its divisors is an integer number (2574520).

Almost surely, 2^21031317 is an apocalyptic number.

It is an amenable number.

21031317 is a deficient number, since it is larger than the sum of its proper divisors (9862923).

21031317 is a wasteful number, since it uses less digits than its factorization.

21031317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39672 (or 39669 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 18.

The square root of 21031317 is about 4585.9913868214. The cubic root of 21031317 is about 276.0294943275.

Adding to 21031317 its reverse (71313012), we get a palindrome (92344329).

The spelling of 21031317 in words is "twenty-one million, thirty-one thousand, three hundred seventeen".