17961 has 4 divisors (see below), whose sum is σ = 23952. Its totient is φ = 11972.

The previous prime is 17959. The next prime is 17971. The reversal of 17961 is 16971.

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: 16971 = 3 ⋅5657.

It is a cyclic number.

It is not a de Polignac number, because 17961 - 2¹ = 17959 is a prime.

It is a D-number.

It is a Curzon number.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (17911) 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, 2991 + ... + 2996.

It is an arithmetic number, because the mean of its divisors is an integer number (5988).

2¹⁷⁹⁶¹ is an apocalyptic number.

It is an amenable number.

17961 is a deficient number, since it is larger than the sum of its proper divisors (5991).

17961 is an equidigital number, since it uses as much as digits as its factorization.

17961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5990.

The product of its digits is 378, while the sum is 24.

The square root of 17961 is about 134.0186554178. The cubic root of 17961 is about 26.1884726790.

Subtracting from 17961 its reverse (16971), we obtain a triangular number (990 = T₄₄).

The spelling of 17961 in words is "seventeen thousand, nine hundred sixty-one".