21117697 has 2 divisors, whose sum is σ = 21117698. Its totient is φ = 21117696.

The previous prime is 21117671. The next prime is 21117709. The reversal of 21117697 is 79671112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15992001 + 5125696 = 3999^2 + 2264^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21117697 is a prime.

It is not a weakly prime, because it can be changed into another prime (21117647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10558848 + 10558849.

It is an arithmetic number, because the mean of its divisors is an integer number (10558849).

Almost surely, 2^21117697 is an apocalyptic number.

It is an amenable number.

21117697 is a deficient number, since it is larger than the sum of its proper divisors (1).

21117697 is an equidigital number, since it uses as much as digits as its factorization.

21117697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5292, while the sum is 34.

The square root of 21117697 is about 4595.3995473734. The cubic root of 21117697 is about 276.4068816732.

The spelling of 21117697 in words is "twenty-one million, one hundred seventeen thousand, six hundred ninety-seven".