646780 has 24 divisors (see below), whose sum is σ = 1379952. Its totient is φ = 254592.

The previous prime is 646771. The next prime is 646781. The reversal of 646780 is 87646.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646781) 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 7 ways as a sum of consecutive naturals, for example, 1239 + ... + 1681.

It is an arithmetic number, because the mean of its divisors is an integer number (57498).

2⁶⁴⁶⁷⁸⁰ is an apocalyptic number.

It is an amenable number.

646780 is an abundant number, since it is smaller than the sum of its proper divisors (733172).

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

646780 is a wasteful number, since it uses less digits than its factorization.

646780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 525 (or 523 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 646780 is about 804.2263363009. The cubic root of 646780 is about 86.4806331730.

The spelling of 646780 in words is "six hundred forty-six thousand, seven hundred eighty".