155820 has 72 divisors (see below), whose sum is σ = 517104. Its totient is φ = 34944.

The previous prime is 155809. The next prime is 155821. The reversal of 155820 is 28551.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a nialpdrome in base 12.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 155820.

It is not an unprimeable number, because it can be changed into a prime (155821) 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 23 ways as a sum of consecutive naturals, for example, 2914 + ... + 2966.

It is an arithmetic number, because the mean of its divisors is an integer number (7182).

2¹⁵⁵⁸²⁰ is an apocalyptic number.

155820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 155820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (258552).

155820 is an abundant number, since it is smaller than the sum of its proper divisors (361284).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

155820 is a wasteful number, since it uses less digits than its factorization.

155820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79 (or 70 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 155820 is about 394.7404210364. The cubic root of 155820 is about 53.8114134885.

The spelling of 155820 in words is "one hundred fifty-five thousand, eight hundred twenty".