155989 has 4 divisors (see below), whose sum is σ = 156780. Its totient is φ = 155200.

The previous prime is 155921. The next prime is 156007. The reversal of 155989 is 989551.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 108900 + 47089 = 330^2 + 217^2 .

It is a cyclic number.

It is not a de Polignac number, because 155989 - 2⁷ = 155861 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155689) 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, 189 + ... + 589.

It is an arithmetic number, because the mean of its divisors is an integer number (39195).

2¹⁵⁵⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

155989 is a deficient number, since it is larger than the sum of its proper divisors (791).

155989 is an equidigital number, since it uses as much as digits as its factorization.

155989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 790.

The product of its digits is 16200, while the sum is 37.

The square root of 155989 is about 394.9544277508. The cubic root of 155989 is about 53.8308608061.

The spelling of 155989 in words is "one hundred fifty-five thousand, nine hundred eighty-nine".