661841 has 4 divisors (see below), whose sum is σ = 667812. Its totient is φ = 655872.

The previous prime is 661823. The next prime is 661849. The reversal of 661841 is 148166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 297025 + 364816 = 545^2 + 604^2 .

It is a cyclic number.

It is not a de Polignac number, because 661841 - 2⁶ = 661777 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661841.

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, 2816 + ... + 3041.

It is an arithmetic number, because the mean of its divisors is an integer number (166953).

2⁶⁶¹⁸⁴¹ is an apocalyptic number.

It is an amenable number.

661841 is a deficient number, since it is larger than the sum of its proper divisors (5971).

661841 is a wasteful number, since it uses less digits than its factorization.

661841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5970.

The product of its digits is 1152, while the sum is 26.

The square root of 661841 is about 813.5361086024. The cubic root of 661841 is about 87.1467554341.

The spelling of 661841 in words is "six hundred sixty-one thousand, eight hundred forty-one".