6689999 has 2 divisors, whose sum is σ = 6690000. Its totient is φ = 6689998.

The previous prime is 6689989. The next prime is 6690001. The reversal of 6689999 is 9999866.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6689999 - 2¹⁶ = 6624463 is a prime.

It is a Sophie Germain prime.

Together with 6690001, it forms a pair of twin primes.

It is a Chen prime.

6689999 is a modest number, since divided by 9999 gives 668 as remainder.

It is a plaindrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6689909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3344999 + 3345000.

It is an arithmetic number, because the mean of its divisors is an integer number (3345000).

Almost surely, 2^6689999 is an apocalyptic number.

6689999 is a deficient number, since it is larger than the sum of its proper divisors (1).

6689999 is an equidigital number, since it uses as much as digits as its factorization.

6689999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1889568, while the sum is 56.

The square root of 6689999 is about 2586.5032379643. The cubic root of 6689999 is about 188.4265157872.

The spelling of 6689999 in words is "six million, six hundred eighty-nine thousand, nine hundred ninety-nine".