39961 has 4 divisors (see below), whose sum is σ = 40500. Its totient is φ = 39424.

The previous prime is 39953. The next prime is 39971. The reversal of 39961 is 16993.

It is a happy number.

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 15625 + 24336 = 125^2 + 156^2 .

It is a cyclic number.

It is not a de Polignac number, because 39961 - 2³ = 39953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (39901) 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, 136 + ... + 313.

It is an arithmetic number, because the mean of its divisors is an integer number (10125).

2³⁹⁹⁶¹ is an apocalyptic number.

It is an amenable number.

39961 is a deficient number, since it is larger than the sum of its proper divisors (539).

39961 is an equidigital number, since it uses as much as digits as its factorization.

39961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538.

The product of its digits is 1458, while the sum is 28.

The square root of 39961 is about 199.9024762228. The cubic root of 39961 is about 34.1884004756.

Subtracting from 39961 its product of digits (1458), we obtain a triangular number (38503 = T₂₇₇).

It can be divided in two parts, 39 and 961, that added together give a cube (1000 = 10³).

The spelling of 39961 in words is "thirty-nine thousand, nine hundred sixty-one".