143991 has 8 divisors (see below), whose sum is σ = 213360. Its totient is φ = 95976.

The previous prime is 143981. The next prime is 143999. The reversal of 143991 is 199341.

It is not a de Polignac number, because 143991 - 2¹³ = 135799 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 5333 = 143991 / (1 + 4 + 3 + 9 + 9 + 1).

143991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (143999) 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, 2640 + ... + 2693.

It is an arithmetic number, because the mean of its divisors is an integer number (26670).

2¹⁴³⁹⁹¹ is an apocalyptic number.

143991 is a deficient number, since it is larger than the sum of its proper divisors (69369).

143991 is an equidigital number, since it uses as much as digits as its factorization.

143991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5342 (or 5336 counting only the distinct ones).

The product of its digits is 972, while the sum is 27.

The square root of 143991 is about 379.4614604937. The cubic root of 143991 is about 52.4137358858.

It can be divided in two parts, 14399 and 1, that added together give a square (14400 = 120²).

The spelling of 143991 in words is "one hundred forty-three thousand, nine hundred ninety-one".