40561 has 4 divisors (see below), whose sum is σ = 41472. Its totient is φ = 39652.

The previous prime is 40559. The next prime is 40577. The reversal of 40561 is 16504.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 40561 - 2¹ = 40559 is a prime.

It is a Duffinian number.

40561 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (40531) 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, 385 + ... + 478.

It is an arithmetic number, because the mean of its divisors is an integer number (10368).

2⁴⁰⁵⁶¹ is an apocalyptic number.

It is an amenable number.

40561 is a deficient number, since it is larger than the sum of its proper divisors (911).

40561 is an equidigital number, since it uses as much as digits as its factorization.

40561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 910.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 40561 is about 201.3976166691. The cubic root of 40561 is about 34.3586600027.

The spelling of 40561 in words is "forty thousand, five hundred sixty-one".