21344417 has 2 divisors, whose sum is σ = 21344418. Its totient is φ = 21344416.

The previous prime is 21344369. The next prime is 21344419. The reversal of 21344417 is 71444312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20802721 + 541696 = 4561^2 + 736^2 .

It is a cyclic number.

It is not a de Polignac number, because 21344417 - 2²² = 17150113 is a prime.

Together with 21344419, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1350368 and since 21344417 and 1350368 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21344419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10672208 + 10672209.

It is an arithmetic number, because the mean of its divisors is an integer number (10672209).

Almost surely, 2^21344417 is an apocalyptic number.

It is an amenable number.

21344417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21344417 is an equidigital number, since it uses as much as digits as its factorization.

21344417 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 26.

The square root of 21344417 is about 4620.0018398265. The cubic root of 21344417 is about 277.3925325823.

Adding to 21344417 its reverse (71444312), we get a palindrome (92788729).

The spelling of 21344417 in words is "twenty-one million, three hundred forty-four thousand, four hundred seventeen".