646638 has 8 divisors (see below), whose sum is σ = 1293288. Its totient is φ = 215544.

The previous prime is 646637. The next prime is 646643. The reversal of 646638 is 836646.

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

646638 is an admirable number.

It is a Curzon number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 646599 and 646608.

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 646638.

It is not an unprimeable number, because it can be changed into a prime (646631) 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, 53881 + ... + 53892.

It is an arithmetic number, because the mean of its divisors is an integer number (161661).

2⁶⁴⁶⁶³⁸ is an apocalyptic number.

646638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646638 is a wasteful number, since it uses less digits than its factorization.

646638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107778.

The product of its digits is 20736, while the sum is 33.

The square root of 646638 is about 804.1380478500. The cubic root of 646638 is about 86.4743037932.

The spelling of 646638 in words is "six hundred forty-six thousand, six hundred thirty-eight".