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2155 = 5431

2155 has 4 divisors (see below), whose sum is σ = 2592. Its totient is φ = 1720.

The previous prime is 2153. The next prime is 2161. The reversal of 2155 is 5512.

2155 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 2155 - 21 = 2153 is a prime.

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a plaindrome in base 11 and base 14.

It is a nialpdrome in base 5.

It is not an unprimeable number, because it can be changed into a prime (2153) 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, 211 + ... + 220.

It is an arithmetic number, because the mean of its divisors is an integer number (648).

22155 is an apocalyptic number.

2155 is a deficient number, since it is larger than the sum of its proper divisors (437).

2155 is an equidigital number, since it uses as much as digits as its factorization.

2155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 436.

The product of its digits is 50, while the sum is 13.

The square root of 2155 is about 46.4219775537. The cubic root of 2155 is about 12.9166261994.

Adding to 2155 its reverse (5512), we get a palindrome (7667).

The spelling of 2155 in words is "two thousand, one hundred fifty-five".

Divisors: 1 5 431 2155