2155821173 has 4 divisors (see below), whose sum is σ = 2351804928. Its totient is φ = 1959837420.

The previous prime is 2155821137. The next prime is 2155821193. The reversal of 2155821173 is 3711285512.

2155821173 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, 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 2155821173 - 2¹² = 2155817077 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2155821193) 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, 97991861 + ... + 97991882.

It is an arithmetic number, because the mean of its divisors is an integer number (587951232).

Almost surely, 2^2155821173 is an apocalyptic number.

It is an amenable number.

2155821173 is a deficient number, since it is larger than the sum of its proper divisors (195983755).

2155821173 is a wasteful number, since it uses less digits than its factorization.

2155821173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195983754.

The product of its digits is 16800, while the sum is 35.

The square root of 2155821173 is about 46430.8213690001. The cubic root of 2155821173 is about 1291.8266638369.

It can be divided in two parts, 2155 and 821173, that added together give a palindrome (823328).

The spelling of 2155821173 in words is "two billion, one hundred fifty-five million, eight hundred twenty-one thousand, one hundred seventy-three".