646999 has 4 divisors (see below), whose sum is σ = 655936. Its totient is φ = 638064.

The previous prime is 646993. The next prime is 647011. The reversal of 646999 is 999646.

It is a happy number.

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 646999 - 2³ = 646991 is a prime.

It is a Duffinian number.

646999 is a modest number, since divided by 999 gives 646 as remainder.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646991) 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, 4359 + ... + 4504.

It is an arithmetic number, because the mean of its divisors is an integer number (163984).

2⁶⁴⁶⁹⁹⁹ is an apocalyptic number.

646999 is a deficient number, since it is larger than the sum of its proper divisors (8937).

646999 is an equidigital number, since it uses as much as digits as its factorization.

646999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8936.

The product of its digits is 104976, while the sum is 43.

The square root of 646999 is about 804.3624804776. The cubic root of 646999 is about 86.4903928653.

The spelling of 646999 in words is "six hundred forty-six thousand, nine hundred ninety-nine".