21126317 has 2 divisors, whose sum is σ = 21126318. Its totient is φ = 21126316.

The previous prime is 21126293. The next prime is 21126337. The reversal of 21126317 is 71362112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19412836 + 1713481 = 4406^2 + 1309^2 .

It is a cyclic number.

It is not a de Polignac number, because 21126317 - 2⁶ = 21126253 is a prime.

It is a Chen prime.

It is equal to p_1337450 and since 21126317 and 1337450 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 21126292 and 21126301.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21126337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10563158 + 10563159.

It is an arithmetic number, because the mean of its divisors is an integer number (10563159).

Almost surely, 2^21126317 is an apocalyptic number.

It is an amenable number.

21126317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21126317 is an equidigital number, since it uses as much as digits as its factorization.

21126317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 504, while the sum is 23.

The square root of 21126317 is about 4596.3373461921. The cubic root of 21126317 is about 276.4444852560. Note that the first 4 decimals are identical.

Adding to 21126317 its reverse (71362112), we get a palindrome (92488429).

The spelling of 21126317 in words is "twenty-one million, one hundred twenty-six thousand, three hundred seventeen".