50991 has 8 divisors (see below), whose sum is σ = 71040. Its totient is φ = 32472.

The previous prime is 50989. The next prime is 50993. The reversal of 50991 is 19905.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (50989) and next prime (50993).

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

It is not a de Polignac number, because 50991 - 2¹ = 50989 is a prime.

50991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (50993) 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, 301 + ... + 438.

It is an arithmetic number, because the mean of its divisors is an integer number (8880).

2⁵⁰⁹⁹¹ is an apocalyptic number.

50991 is a deficient number, since it is larger than the sum of its proper divisors (20049).

50991 is a wasteful number, since it uses less digits than its factorization.

50991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 765.

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

The square root of 50991 is about 225.8118685986. The cubic root of 50991 is about 37.0821161351.

Adding to 50991 its sum of digits (24), we get a palindrome (51015).

The spelling of 50991 in words is "fifty thousand, nine hundred ninety-one".