6391669 has 2 divisors, whose sum is σ = 6391670. Its totient is φ = 6391668.

The previous prime is 6391667. The next prime is 6391699. The reversal of 6391669 is 9661936.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5152900 + 1238769 = 2270^2 + 1113^2 .

It is a cyclic number.

It is not a de Polignac number, because 6391669 - 2¹ = 6391667 is a prime.

It is a super-2 number, since 2×6391669² = 81706865211122, which contains 22 as substring.

Together with 6391667, it forms a pair of twin primes.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6391663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3195834 + 3195835.

It is an arithmetic number, because the mean of its divisors is an integer number (3195835).

Almost surely, 2^6391669 is an apocalyptic number.

It is an amenable number.

6391669 is a deficient number, since it is larger than the sum of its proper divisors (1).

6391669 is an equidigital number, since it uses as much as digits as its factorization.

6391669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52488, while the sum is 40.

The square root of 6391669 is about 2528.1750334975. The cubic root of 6391669 is about 185.5829577873.

The spelling of 6391669 in words is "six million, three hundred ninety-one thousand, six hundred sixty-nine".