647745 has 32 divisors (see below), whose sum is σ = 1228800. Its totient is φ = 285120.

The previous prime is 647743. The next prime is 647747. The reversal of 647745 is 547746.

It is an interprime number because it is at equal distance from previous prime (647743) and next prime (647747).

It is not a de Polignac number, because 647745 - 2¹ = 647743 is a prime.

Its product of digits (23520) is a multiple of the sum of its prime divisors (245).

It is a Curzon number.

647745 is a lucky number.

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 647745.

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 31 ways as a sum of consecutive naturals, for example, 3156 + ... + 3354.

It is an arithmetic number, because the mean of its divisors is an integer number (38400).

2⁶⁴⁷⁷⁴⁵ is an apocalyptic number.

647745 is the 465-th octagonal number.

It is an amenable number.

647745 is a deficient number, since it is larger than the sum of its proper divisors (581055).

647745 is a wasteful number, since it uses less digits than its factorization.

647745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245.

The product of its digits is 23520, while the sum is 33.

The square root of 647745 is about 804.8260681663. The cubic root of 647745 is about 86.5236216909.

Subtracting from 647745 its reverse (547746), we obtain a palindrome (99999).

The spelling of 647745 in words is "six hundred forty-seven thousand, seven hundred forty-five".