647856 has 60 divisors (see below), whose sum is σ = 1982760. Its totient is φ = 195840.

The previous prime is 647851. The next prime is 647861. The reversal of 647856 is 658746.

It is a happy number.

647856 is a `hidden beast` number, since 647 + 8 + 5 + 6 = 666.

It is an interprime number because it is at equal distance from previous prime (647851) and next prime (647861).

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

It is a self number, because there is not a number n which added to its sum of digits gives 647856.

It is not an unprimeable number, because it can be changed into a prime (647851) by changing a digit.

647856 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1380 + ... + 1788.

It is an arithmetic number, because the mean of its divisors is an integer number (33046).

2⁶⁴⁷⁸⁵⁶ is an apocalyptic number.

647856 is a gapful number since it is divisible by the number (66) 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 647856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (991380).

647856 is an abundant number, since it is smaller than the sum of its proper divisors (1334904).

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

647856 is a wasteful number, since it uses less digits than its factorization.

647856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434 (or 425 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 647856 is about 804.8950242112. The cubic root of 647856 is about 86.5285637455.

The spelling of 647856 in words is "six hundred forty-seven thousand, eight hundred fifty-six".