647561 has 4 divisors (see below), whose sum is σ = 653952. Its totient is φ = 641172.

The previous prime is 647557. The next prime is 647579. The reversal of 647561 is 165746.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 647561 - 2² = 647557 is a prime.

It is a Duffinian 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 647561.

It is not an unprimeable number, because it can be changed into a prime (647531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3041 + ... + 3246.

It is an arithmetic number, because the mean of its divisors is an integer number (163488).

2⁶⁴⁷⁵⁶¹ is an apocalyptic number.

It is an amenable number.

647561 is a deficient number, since it is larger than the sum of its proper divisors (6391).

647561 is a wasteful number, since it uses less digits than its factorization.

647561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6390.

The product of its digits is 5040, while the sum is 29.

The square root of 647561 is about 804.7117496346. The cubic root of 647561 is about 86.5154282124.

The spelling of 647561 in words is "six hundred forty-seven thousand, five hundred sixty-one".