155993 has 4 divisors (see below), whose sum is σ = 159360. Its totient is φ = 152628.

The previous prime is 155921. The next prime is 156007. The reversal of 155993 is 399551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 155993 - 2¹² = 151897 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (155593) 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, 1613 + ... + 1706.

It is an arithmetic number, because the mean of its divisors is an integer number (39840).

2¹⁵⁵⁹⁹³ is an apocalyptic number.

It is an amenable number.

155993 is a deficient number, since it is larger than the sum of its proper divisors (3367).

155993 is an equidigital number, since it uses as much as digits as its factorization.

155993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3366.

The product of its digits is 6075, while the sum is 32.

The square root of 155993 is about 394.9594915938. The cubic root of 155993 is about 53.8313209275.

Adding to 155993 its sum of digits (32), we get a square (156025 = 395²).

Subtracting from 155993 its sum of digits (32), we obtain a triangular number (155961 = T₅₅₈).

The spelling of 155993 in words is "one hundred fifty-five thousand, nine hundred ninety-three".