647744 has 28 divisors (see below), whose sum is σ = 1333500. Its totient is φ = 311808.

The previous prime is 647743. The next prime is 647747. The reversal of 647744 is 447746.

It can be written as a sum of positive squares in 2 ways, for example, as 409600 + 238144 = 640^2 + 488^2 .

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 647744.

It is not an unprimeable number, because it can be changed into a prime (647741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1682 + ... + 2030.

It is an arithmetic number, because the mean of its divisors is an integer number (47625).

2⁶⁴⁷⁷⁴⁴ is an apocalyptic number.

647744 is a gapful number since it is divisible by the number (64) 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 647744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (666750).

647744 is an abundant number, since it is smaller than the sum of its proper divisors (685756).

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

647744 is a wasteful number, since it uses less digits than its factorization.

647744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 390 (or 380 counting only the distinct ones).

The product of its digits is 18816, while the sum is 32.

The square root of 647744 is about 804.8254469138. The cubic root of 647744 is about 86.5235771653.

It can be divided in two parts, 64 and 7744, that multiplied together give a square (495616 = 704²).

The spelling of 647744 in words is "six hundred forty-seven thousand, seven hundred forty-four".