646646 has 64 divisors (see below), whose sum is σ = 1451520. Its totient is φ = 207360.

The previous prime is 646643. The next prime is 646669.

646646 = 85² + 86² + ... + 136².

It is a happy number.

646646 is nontrivially palindromic in base 10 and base 12.

646646 is a nontrivial binomial coefficient, being equal to C(22, 10).

It is a congruent number.

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

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34025 + ... + 34043.

It is an arithmetic number, because the mean of its divisors is an integer number (22680).

2⁶⁴⁶⁶⁴⁶ is an apocalyptic number.

646646 is an abundant number, since it is smaller than the sum of its proper divisors (804874).

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

646646 is a wasteful number, since it uses less digits than its factorization.

646646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69.

The product of its digits is 20736, while the sum is 32.

The square root of 646646 is about 804.1430221049. The cubic root of 646646 is about 86.4746604026.

The spelling of 646646 in words is "six hundred forty-six thousand, six hundred forty-six".