9951 has 8 divisors (see below), whose sum is σ = 13824. Its totient is φ = 6360.

The previous prime is 9949. The next prime is 9967. The reversal of 9951 is 1599.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 9951 - 2¹ = 9949 is a prime.

It is a plaindrome in base 8, base 14 and base 16.

It is a nialpdrome in base 10.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 9951.

It is not an unprimeable number, because it can be changed into a prime (9901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40 + ... + 146.

It is an arithmetic number, because the mean of its divisors is an integer number (1728).

2⁹⁹⁵¹ is an apocalyptic number.

9951 is a deficient number, since it is larger than the sum of its proper divisors (3873).

9951 is a wasteful number, since it uses less digits than its factorization.

9951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141.

The product of its digits is 405, while the sum is 24.

The square root of 9951 is about 99.7546991374. The cubic root of 9951 is about 21.5091001679.

The spelling of 9951 in words is "nine thousand, nine hundred fifty-one".