647731 has 6 divisors (see below), whose sum is σ = 753540. Its totient is φ = 555156.

The previous prime is 647723. The next prime is 647741. The reversal of 647731 is 137746.

647731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 647731 - 2³ = 647723 is a prime.

It is a super-2 number, since 2×647731² = 839110896722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 647731.

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

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6561 + ... + 6658.

It is an arithmetic number, because the mean of its divisors is an integer number (125590).

2⁶⁴⁷⁷³¹ is an apocalyptic number.

647731 is a deficient number, since it is larger than the sum of its proper divisors (105809).

647731 is a wasteful number, since it uses less digits than its factorization.

647731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13233 (or 13226 counting only the distinct ones).

The product of its digits is 3528, while the sum is 28.

The square root of 647731 is about 804.8173705879. The cubic root of 647731 is about 86.5229983286.

It can be divided in two parts, 647 and 731, that added together give a triangular number (1378 = T₅₂).

The spelling of 647731 in words is "six hundred forty-seven thousand, seven hundred thirty-one".