6391866 has 48 divisors (see below), whose sum is σ = 14593824. Its totient is φ = 1855008.

The previous prime is 6391841. The next prime is 6391877. The reversal of 6391866 is 6681936.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28045 + ... + 28271.

It is an arithmetic number, because the mean of its divisors is an integer number (304038).

Almost surely, 2^6391866 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6391866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7296912).

6391866 is an abundant number, since it is smaller than the sum of its proper divisors (8201958).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6391866 is a wasteful number, since it uses less digits than its factorization.

6391866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283 (or 264 counting only the distinct ones).

The product of its digits is 46656, while the sum is 39.

The square root of 6391866 is about 2528.2139941073. The cubic root of 6391866 is about 185.5848644081.

It can be divided in two parts, 6 and 391866, that multiplied together give a triangular number (2351196 = T₂₁₆₈).

The spelling of 6391866 in words is "six million, three hundred ninety-one thousand, eight hundred sixty-six".