21552317 has 2 divisors, whose sum is σ = 21552318. Its totient is φ = 21552316.

The previous prime is 21552283. The next prime is 21552319. The reversal of 21552317 is 71325512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21335161 + 217156 = 4619^2 + 466^2 .

It is a cyclic number.

It is not a de Polignac number, because 21552317 - 2¹² = 21548221 is a prime.

It is a super-3 number, since 3×21552317³ (a number of 23 digits) contains 333 as substring.

Together with 21552319, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21552319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776158 + 10776159.

It is an arithmetic number, because the mean of its divisors is an integer number (10776159).

Almost surely, 2^21552317 is an apocalyptic number.

It is an amenable number.

21552317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21552317 is an equidigital number, since it uses as much as digits as its factorization.

21552317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2100, while the sum is 26.

The square root of 21552317 is about 4642.4473071862. The cubic root of 21552317 is about 278.2902485890.

Adding to 21552317 its reverse (71325512), we get a palindrome (92877829).

The spelling of 21552317 in words is "twenty-one million, five hundred fifty-two thousand, three hundred seventeen".