9961 has 4 divisors (see below), whose sum is σ = 11392. Its totient is φ = 8532.

The previous prime is 9949. The next prime is 9967. The reversal of 9961 is 1699.

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 9961 - 2⁵ = 9929 is a prime.

It is an Ulam number.

It is a Duffinian number.

9961 is a lucky number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (9967) 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, 705 + ... + 718.

It is an arithmetic number, because the mean of its divisors is an integer number (2848).

2⁹⁹⁶¹ is an apocalyptic number.

It is an amenable number.

9961 is a deficient number, since it is larger than the sum of its proper divisors (1431).

9961 is a wasteful number, since it uses less digits than its factorization.

9961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1430.

The product of its digits is 486, while the sum is 25.

The square root of 9961 is about 99.8048095034. The cubic root of 9961 is about 21.5163027603.

It can be divided in two parts, 9 and 961, that multiplied together give a square (8649 = 93²).

The spelling of 9961 in words is "nine thousand, nine hundred sixty-one".