646659 has 12 divisors (see below), whose sum is σ = 1006096. Its totient is φ = 397872.

The previous prime is 646643. The next prime is 646669. The reversal of 646659 is 956646.

646659 = 217² + 218² + ... + 229².

It is a happy number.

646659 is a `hidden beast` number, since 646 + 6 + 5 + 9 = 666.

646659 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 646659 - 2⁴ = 646643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (646609) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2647 + ... + 2880.

2⁶⁴⁶⁶⁵⁹ is an apocalyptic number.

646659 is a deficient number, since it is larger than the sum of its proper divisors (359437).

646659 is a wasteful number, since it uses less digits than its factorization.

646659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5546 (or 5543 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The square root of 646659 is about 804.1511052035. The cubic root of 646659 is about 86.4752398866.

It can be divided in two parts, 6 and 46659, that added together give a triangular number (46665 = T₃₀₅).

The spelling of 646659 in words is "six hundred forty-six thousand, six hundred fifty-nine".