647679 has 4 divisors (see below), whose sum is σ = 863576. Its totient is φ = 431784.

The previous prime is 647663. The next prime is 647687. The reversal of 647679 is 976746.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 647679 - 2⁴ = 647663 is a prime.

It is a D-number.

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 647679.

It is not an unprimeable number, because it can be changed into a prime (647609) 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, 107944 + ... + 107949.

It is an arithmetic number, because the mean of its divisors is an integer number (215894).

2⁶⁴⁷⁶⁷⁹ is an apocalyptic number.

647679 is a deficient number, since it is larger than the sum of its proper divisors (215897).

647679 is a wasteful number, since it uses less digits than its factorization.

647679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215896.

The product of its digits is 63504, while the sum is 39.

The square root of 647679 is about 804.7850644737. The cubic root of 647679 is about 86.5206829043.

It can be divided in two parts, 6476 and 79, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 647679 in words is "six hundred forty-seven thousand, six hundred seventy-nine".