15961 has 4 divisors (see below), whose sum is σ = 17424. Its totient is φ = 14500.

The previous prime is 15959. The next prime is 15971. The reversal of 15961 is 16951.

15961 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 15961 - 2¹ = 15959 is a prime.

It is not an unprimeable number, because it can be changed into a prime (15901) 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, 715 + ... + 736.

It is an arithmetic number, because the mean of its divisors is an integer number (4356).

2¹⁵⁹⁶¹ is an apocalyptic number.

15961 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

15961 is the 57-th centered decagonal number.

It is an amenable number.

15961 is a deficient number, since it is larger than the sum of its proper divisors (1463).

15961 is a wasteful number, since it uses less digits than its factorization.

15961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1462.

The product of its digits is 270, while the sum is 22.

The square root of 15961 is about 126.3368513143. The cubic root of 15961 is about 25.1779306234.

Subtracting 15961 from its reverse (16951), we obtain a triangular number (990 = T₄₄).

The spelling of 15961 in words is "fifteen thousand, nine hundred sixty-one".