6391728 has 120 divisors (see below), whose sum is σ = 21703968. Its totient is φ = 1714176.

The previous prime is 6391727. The next prime is 6391729. The reversal of 6391728 is 8271936.

6391728 is a `hidden beast` number, since 639 + 17 + 2 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (6391727) and next prime (6391729).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is one of the 548 Lynch-Bell numbers.

It is a junction number, because it is equal to n+sod(n) for n = 6391692 and 6391701.

It is not an unprimeable number, because it can be changed into a prime (6391727) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16950 + ... + 17322.

Almost surely, 2^6391728 is an apocalyptic number.

6391728 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6391728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10851984).

6391728 is an abundant number, since it is smaller than the sum of its proper divisors (15312240).

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

6391728 is a wasteful number, since it uses less digits than its factorization.

6391728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411 (or 402 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 6391728 is about 2528.1867019665. The cubic root of 6391728 is about 185.5835288098.

The spelling of 6391728 in words is "six million, three hundred ninety-one thousand, seven hundred twenty-eight".