646679 has 4 divisors (see below), whose sum is σ = 705480. Its totient is φ = 587880.

The previous prime is 646669. The next prime is 646687. The reversal of 646679 is 976646.

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

It is a cyclic number.

It is not a de Polignac number, because 646679 - 2⁸ = 646423 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646609) 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, 29384 + ... + 29405.

It is an arithmetic number, because the mean of its divisors is an integer number (176370).

2⁶⁴⁶⁶⁷⁹ is an apocalyptic number.

646679 is a deficient number, since it is larger than the sum of its proper divisors (58801).

646679 is a wasteful number, since it uses less digits than its factorization.

646679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58800.

The product of its digits is 54432, while the sum is 38.

The square root of 646679 is about 804.1635405811. The cubic root of 646679 is about 86.4761313853.

The spelling of 646679 in words is "six hundred forty-six thousand, six hundred seventy-nine".