641781 has 24 divisors (see below), whose sum is σ = 1083264. Its totient is φ = 358560.

The previous prime is 641761. The next prime is 641789. The reversal of 641781 is 187146.

It is a happy number.

It is not a de Polignac number, because 641781 - 2⁵ = 641749 is a prime.

It is a super-2 number, since 2×641781² = 823765703922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 641781.

It is not an unprimeable number, because it can be changed into a prime (641789) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3760 + ... + 3926.

It is an arithmetic number, because the mean of its divisors is an integer number (45136).

2⁶⁴¹⁷⁸¹ is an apocalyptic number.

641781 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

641781 is a deficient number, since it is larger than the sum of its proper divisors (441483).

641781 is a wasteful number, since it uses less digits than its factorization.

641781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241 (or 238 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 641781 is about 801.1123516711. The cubic root of 641781 is about 86.2572520682.

The spelling of 641781 in words is "six hundred forty-one thousand, seven hundred eighty-one".