6921688817 has 2 divisors, whose sum is σ = 6921688818. Its totient is φ = 6921688816.

The previous prime is 6921688759. The next prime is 6921688819. The reversal of 6921688817 is 7188861296.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4552335841 + 2369352976 = 67471^2 + 48676^2 .

It is a cyclic number.

It is not a de Polignac number, because 6921688817 - 2¹⁶ = 6921623281 is a prime.

Together with 6921688819, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (6921688819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3460844408 + 3460844409.

It is an arithmetic number, because the mean of its divisors is an integer number (3460844409).

Almost surely, 2^6921688817 is an apocalyptic number.

It is an amenable number.

6921688817 is a deficient number, since it is larger than the sum of its proper divisors (1).

6921688817 is an equidigital number, since it uses as much as digits as its factorization.

6921688817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2322432, while the sum is 56.

The square root of 6921688817 is about 83196.6875362235. The cubic root of 6921688817 is about 1905.7708953262.

The spelling of 6921688817 in words is "six billion, nine hundred twenty-one million, six hundred eighty-eight thousand, eight hundred seventeen".