181987 has 4 divisors (see below), whose sum is σ = 196000. Its totient is φ = 167976.

The previous prime is 181981. The next prime is 181997. The reversal of 181987 is 789181.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 181987 - 2¹¹ = 179939 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181981) 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, 6987 + ... + 7012.

It is an arithmetic number, because the mean of its divisors is an integer number (49000).

2¹⁸¹⁹⁸⁷ is an apocalyptic number.

181987 is a deficient number, since it is larger than the sum of its proper divisors (14013).

181987 is a wasteful number, since it uses less digits than its factorization.

181987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14012.

The product of its digits is 4032, while the sum is 34.

The square root of 181987 is about 426.5993436469. The cubic root of 181987 is about 56.6691617510.

The spelling of 181987 in words is "one hundred eighty-one thousand, nine hundred eighty-seven".