6991889 has 2 divisors, whose sum is σ = 6991890. Its totient is φ = 6991888.

The previous prime is 6991877. The next prime is 6991903. The reversal of 6991889 is 9881996.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6838225 + 153664 = 2615^2 + 392^2 .

It is a cyclic number.

It is not a de Polignac number, because 6991889 - 2¹² = 6987793 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an Ulam number.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (6991819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3495944 + 3495945.

It is an arithmetic number, because the mean of its divisors is an integer number (3495945).

Almost surely, 2^6991889 is an apocalyptic number.

It is an amenable number.

6991889 is a deficient number, since it is larger than the sum of its proper divisors (1).

6991889 is an equidigital number, since it uses as much as digits as its factorization.

6991889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 279936, while the sum is 50.

The square root of 6991889 is about 2644.2180318574. The cubic root of 6991889 is about 191.2192050321.

It can be divided in two parts, 69918 and 89, that added together give a palindrome (70007).

The spelling of 6991889 in words is "six million, nine hundred ninety-one thousand, eight hundred eighty-nine".