661844 has 12 divisors (see below), whose sum is σ = 1226484. Its totient is φ = 311424.

The previous prime is 661823. The next prime is 661849. The reversal of 661844 is 448166.

It can be written as a sum of positive squares in 2 ways, for example, as 547600 + 114244 = 740^2 + 338^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661849) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4799 + ... + 4934.

It is an arithmetic number, because the mean of its divisors is an integer number (102207).

2⁶⁶¹⁸⁴⁴ is an apocalyptic number.

It is an amenable number.

661844 is a deficient number, since it is larger than the sum of its proper divisors (564640).

661844 is a wasteful number, since it uses less digits than its factorization.

661844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9754 (or 9752 counting only the distinct ones).

The product of its digits is 4608, while the sum is 29.

The square root of 661844 is about 813.5379524030. The cubic root of 661844 is about 87.1468871071.

It can be divided in two parts, 6618 and 44, that multiplied together give a palindrome (291192).

The spelling of 661844 in words is "six hundred sixty-one thousand, eight hundred forty-four".