647640 has 96 divisors (see below), whose sum is σ = 2414880. Its totient is φ = 147456.

The previous prime is 647627. The next prime is 647641. The reversal of 647640 is 46746.

647640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 647640.

It is not an unprimeable number, because it can be changed into a prime (647641) by changing a digit.

647640 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 23 ways as a sum of consecutive naturals, for example, 2392 + ... + 2648.

It is an arithmetic number, because the mean of its divisors is an integer number (25155).

2⁶⁴⁷⁶⁴⁰ is an apocalyptic number.

647640 is a gapful number since it is divisible by the number (60) 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 647640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1207440).

647640 is an abundant number, since it is smaller than the sum of its proper divisors (1767240).

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

647640 is a wasteful number, since it uses less digits than its factorization.

647640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281 (or 274 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 647640 is about 804.7608340370. The cubic root of 647640 is about 86.5189462547.

The spelling of 647640 in words is "six hundred forty-seven thousand, six hundred forty".