155865 has 8 divisors (see below), whose sum is σ = 249408. Its totient is φ = 83120.

The previous prime is 155863. The next prime is 155887. The reversal of 155865 is 568551.

It is a happy number.

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

It is not a de Polignac number, because 155865 - 2¹ = 155863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (155861) 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, 5181 + ... + 5210.

It is an arithmetic number, because the mean of its divisors is an integer number (31176).

2¹⁵⁵⁸⁶⁵ is an apocalyptic number.

155865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

155865 is a deficient number, since it is larger than the sum of its proper divisors (93543).

155865 is a wasteful number, since it uses less digits than its factorization.

155865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10399.

The product of its digits is 6000, while the sum is 30.

The square root of 155865 is about 394.7974164049. The cubic root of 155865 is about 53.8165931414.

Subtracting 155865 from its reverse (568551), we obtain a triangular number (412686 = T₉₀₈).

The spelling of 155865 in words is "one hundred fifty-five thousand, eight hundred sixty-five".