646642 has 8 divisors (see below), whose sum is σ = 1003500. Its totient is φ = 312144.

The previous prime is 646637. The next prime is 646643. The reversal of 646642 is 246646.

It can be written as a sum of positive squares in 2 ways, for example, as 641601 + 5041 = 801^2 + 71^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 646642.

It is not an unprimeable number, because it can be changed into a prime (646643) by changing a digit.

646642 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5517 + ... + 5632.

2⁶⁴⁶⁶⁴² is an apocalyptic number.

646642 is a deficient number, since it is larger than the sum of its proper divisors (356858).

646642 is a wasteful number, since it uses less digits than its factorization.

646642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11180.

The product of its digits is 6912, while the sum is 28.

The square root of 646642 is about 804.1405349813. The cubic root of 646642 is about 86.4744820983.

The spelling of 646642 in words is "six hundred forty-six thousand, six hundred forty-two".