155811 has 8 divisors (see below), whose sum is σ = 209664. Its totient is φ = 102920.

The previous prime is 155809. The next prime is 155821. The reversal of 155811 is 118551.

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

It is a cyclic number.

It is not a de Polignac number, because 155811 - 2¹ = 155809 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 346 + ... + 656.

It is an arithmetic number, because the mean of its divisors is an integer number (26208).

2¹⁵⁵⁸¹¹ is an apocalyptic number.

155811 is a deficient number, since it is larger than the sum of its proper divisors (53853).

155811 is a wasteful number, since it uses less digits than its factorization.

155811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481.

The product of its digits is 200, while the sum is 21.

The square root of 155811 is about 394.7290209751. The cubic root of 155811 is about 53.8103774383.

The spelling of 155811 in words is "one hundred fifty-five thousand, eight hundred eleven".