646720 has 56 divisors (see below), whose sum is σ = 1609344. Its totient is φ = 247296.

The previous prime is 646687. The next prime is 646721. The reversal of 646720 is 27646.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (646721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13737 + ... + 13783.

2⁶⁴⁶⁷²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (804672).

646720 is an abundant number, since it is smaller than the sum of its proper divisors (962624).

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

646720 is a wasteful number, since it uses less digits than its factorization.

646720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 646720 is about 804.1890325042. The cubic root of 646720 is about 86.4779589002.

The spelling of 646720 in words is "six hundred forty-six thousand, seven hundred twenty".