6921389 has 2 divisors, whose sum is σ = 6921390. Its totient is φ = 6921388.

The previous prime is 6921353. The next prime is 6921403. The reversal of 6921389 is 9831296.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6916900 + 4489 = 2630^2 + 67^2 .

It is a cyclic number.

It is not a de Polignac number, because 6921389 - 2⁸ = 6921133 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6921319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3460694 + 3460695.

It is an arithmetic number, because the mean of its divisors is an integer number (3460695).

Almost surely, 2^6921389 is an apocalyptic number.

It is an amenable number.

6921389 is a deficient number, since it is larger than the sum of its proper divisors (1).

6921389 is an equidigital number, since it uses as much as digits as its factorization.

6921389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 38.

The square root of 6921389 is about 2630.8532836325. The cubic root of 6921389 is about 190.5743378402.

The spelling of 6921389 in words is "six million, nine hundred twenty-one thousand, three hundred eighty-nine".