40661 has 4 divisors (see below), whose sum is σ = 41292. Its totient is φ = 40032.

The previous prime is 40639. The next prime is 40693. The reversal of 40661 is 16604.

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 12100 + 28561 = 110^2 + 169^2 .

It is a cyclic number.

It is not a de Polignac number, because 40661 - 2⁶ = 40597 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40361) 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, 206 + ... + 351.

It is an arithmetic number, because the mean of its divisors is an integer number (10323).

2⁴⁰⁶⁶¹ is an apocalyptic number.

It is an amenable number.

40661 is a deficient number, since it is larger than the sum of its proper divisors (631).

40661 is an equidigital number, since it uses as much as digits as its factorization.

40661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 630.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 40661 is about 201.6457289406. The cubic root of 40661 is about 34.3868730336.

The spelling of 40661 in words is "forty thousand, six hundred sixty-one".