21331317 has 36 divisors (see below), whose sum is σ = 34413408. Its totient is φ = 11718000.

The previous prime is 21331313. The next prime is 21331333. The reversal of 21331317 is 71313312.

It is not a de Polignac number, because 21331317 - 2² = 21331313 is a prime.

It is a hoax number, since the sum of its digits (21) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21331293 and 21331302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331313) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 141192 + ... + 141342.

It is an arithmetic number, because the mean of its divisors is an integer number (955928).

Almost surely, 2^21331317 is an apocalyptic number.

It is an amenable number.

21331317 is a deficient number, since it is larger than the sum of its proper divisors (13082091).

21331317 is a wasteful number, since it uses less digits than its factorization.

21331317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 230 (or 192 counting only the distinct ones).

The product of its digits is 378, while the sum is 21.

The square root of 21331317 is about 4618.5838738730. The cubic root of 21331317 is about 277.3357716684.

Adding to 21331317 its reverse (71313312), we get a palindrome (92644629).

The spelling of 21331317 in words is "twenty-one million, three hundred thirty-one thousand, three hundred seventeen".