21020117 has 2 divisors, whose sum is σ = 21020118. Its totient is φ = 21020116.

The previous prime is 21020093. The next prime is 21020119. The reversal of 21020117 is 71102012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17901361 + 3118756 = 4231^2 + 1766^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020117 - 2⁶ = 21020053 is a prime.

Together with 21020119, 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 (21020119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510058 + 10510059.

It is an arithmetic number, because the mean of its divisors is an integer number (10510059).

Almost surely, 2^21020117 is an apocalyptic number.

It is an amenable number.

21020117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020117 is an equidigital number, since it uses as much as digits as its factorization.

21020117 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 21020117 is about 4584.7701141933. The cubic root of 21020117 is about 275.9804867882.

Adding to 21020117 its reverse (71102012), we get a palindrome (92122129).

The spelling of 21020117 in words is "twenty-one million, twenty thousand, one hundred seventeen".