646641 has 6 divisors (see below), whose sum is σ = 934050. Its totient is φ = 431088.

The previous prime is 646637. The next prime is 646643. The reversal of 646641 is 146646.

It can be written as a sum of positive squares in only one way, i.e., 646416 + 225 = 804^2 + 15^2 .

It is not a de Polignac number, because 646641 - 2² = 646637 is a prime.

It is an Ulam number.

It is a Curzon number.

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

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 5 ways as a sum of consecutive naturals, for example, 35916 + ... + 35933.

It is an arithmetic number, because the mean of its divisors is an integer number (155675).

2⁶⁴⁶⁶⁴¹ is an apocalyptic number.

It is an amenable number.

646641 is a deficient number, since it is larger than the sum of its proper divisors (287409).

646641 is a wasteful number, since it uses less digits than its factorization.

646641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71855 (or 71852 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 646641 is about 804.1399131992. The cubic root of 646641 is about 86.4744375221.

The spelling of 646641 in words is "six hundred forty-six thousand, six hundred forty-one".