39561 has 4 divisors (see below), whose sum is σ = 52752. Its totient is φ = 26372.

The previous prime is 39551. The next prime is 39563. The reversal of 39561 is 16593.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16593 = 3 ⋅5531.

It is a cyclic number.

It is not a de Polignac number, because 39561 - 2¹⁵ = 6793 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (39563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6591 + ... + 6596.

It is an arithmetic number, because the mean of its divisors is an integer number (13188).

2³⁹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

39561 is a deficient number, since it is larger than the sum of its proper divisors (13191).

39561 is a wasteful number, since it uses less digits than its factorization.

39561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13190.

The product of its digits is 810, while the sum is 24.

The square root of 39561 is about 198.8994720958. The cubic root of 39561 is about 34.0739451762.

The spelling of 39561 in words is "thirty-nine thousand, five hundred sixty-one".