21368617 has 2 divisors, whose sum is σ = 21368618. Its totient is φ = 21368616.

The previous prime is 21368591. The next prime is 21368629. The reversal of 21368617 is 71686312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17464041 + 3904576 = 4179^2 + 1976^2 .

It is a cyclic number.

It is not a de Polignac number, because 21368617 - 2⁷ = 21368489 is a prime.

It is a super-3 number, since 3×21368617³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21369617) 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 as a sum of consecutive naturals, namely, 10684308 + 10684309.

It is an arithmetic number, because the mean of its divisors is an integer number (10684309).

Almost surely, 2^21368617 is an apocalyptic number.

It is an amenable number.

21368617 is a deficient number, since it is larger than the sum of its proper divisors (1).

21368617 is an equidigital number, since it uses as much as digits as its factorization.

21368617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 34.

The square root of 21368617 is about 4622.6201444635. The cubic root of 21368617 is about 277.4973275721.

The spelling of 21368617 in words is "twenty-one million, three hundred sixty-eight thousand, six hundred seventeen".