21007317 has 4 divisors (see below), whose sum is σ = 28009760. Its totient is φ = 14004876.

The previous prime is 21007307. The next prime is 21007319. The reversal of 21007317 is 71370012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21007317 - 2⁶ = 21007253 is a prime.

It is a Duffinian number.

21007317 is a modest number, since divided by 7317 gives 210 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 21007293 and 21007302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21007319) 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 3 ways as a sum of consecutive naturals, for example, 3501217 + ... + 3501222.

It is an arithmetic number, because the mean of its divisors is an integer number (7002440).

Almost surely, 2^21007317 is an apocalyptic number.

It is an amenable number.

21007317 is a deficient number, since it is larger than the sum of its proper divisors (7002443).

21007317 is an equidigital number, since it uses as much as digits as its factorization.

21007317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7002442.

The product of its (nonzero) digits is 294, while the sum is 21.

The square root of 21007317 is about 4583.3739755774. The cubic root of 21007317 is about 275.9244568509.

Adding to 21007317 its reverse (71370012), we get a palindrome (92377329).

The spelling of 21007317 in words is "twenty-one million, seven thousand, three hundred seventeen".