21707117 has 2 divisors, whose sum is σ = 21707118. Its totient is φ = 21707116.

The previous prime is 21707089. The next prime is 21707137. The reversal of 21707117 is 71170712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21585316 + 121801 = 4646^2 + 349^2 .

It is a cyclic number.

It is not a de Polignac number, because 21707117 - 2⁶ = 21707053 is a prime.

It is a super-5 number, since 5×21707117⁵ (a number of 38 digits) contains 55555 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21707137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10853558 + 10853559.

It is an arithmetic number, because the mean of its divisors is an integer number (10853559).

Almost surely, 2^21707117 is an apocalyptic number.

It is an amenable number.

21707117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21707117 is an equidigital number, since it uses as much as digits as its factorization.

21707117 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 686, while the sum is 26.

The square root of 21707117 is about 4659.0897179599. The cubic root of 21707117 is about 278.9549350611.

Adding to 21707117 its reverse (71170712), we get a palindrome (92877829).

The spelling of 21707117 in words is "twenty-one million, seven hundred seven thousand, one hundred seventeen".