641720 has 32 divisors (see below), whose sum is σ = 1473120. Its totient is φ = 251520.

The previous prime is 641713. The next prime is 641747. The reversal of 641720 is 27146.

641720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 641692 and 641701.

It is a congruent number.

It is an unprimeable number.

641720 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2309 + ... + 2571.

It is an arithmetic number, because the mean of its divisors is an integer number (46035).

2⁶⁴¹⁷²⁰ 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 641720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (736560).

641720 is an abundant number, since it is smaller than the sum of its proper divisors (831400).

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

641720 is a wasteful number, since it uses less digits than its factorization.

641720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335 (or 331 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 641720 is about 801.0742787033. The cubic root of 641720 is about 86.2545191219.

Adding to 641720 its reverse (27146), we get a palindrome (668866).

The spelling of 641720 in words is "six hundred forty-one thousand, seven hundred twenty".