21115417 has 2 divisors, whose sum is σ = 21115418. Its totient is φ = 21115416.

The previous prime is 21115379. The next prime is 21115421. The reversal of 21115417 is 71451112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18412681 + 2702736 = 4291^2 + 1644^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21115417 is a prime.

It is not a weakly prime, because it can be changed into another prime (21115427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557708 + 10557709.

It is an arithmetic number, because the mean of its divisors is an integer number (10557709).

Almost surely, 2^21115417 is an apocalyptic number.

It is an amenable number.

21115417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115417 is an equidigital number, since it uses as much as digits as its factorization.

21115417 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 280, while the sum is 22.

The square root of 21115417 is about 4595.1514664916. The cubic root of 21115417 is about 276.3969337707.

Adding to 21115417 its reverse (71451112), we get a palindrome (92566529).

The spelling of 21115417 in words is "twenty-one million, one hundred fifteen thousand, four hundred seventeen".