2181723 has 4 divisors (see below), whose sum is σ = 2908968. Its totient is φ = 1454480.

The previous prime is 2181719. The next prime is 2181731. The reversal of 2181723 is 3271812.

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

It is a cyclic number.

It is not a de Polignac number, because 2181723 - 2² = 2181719 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 2181693 and 2181702.

It is not an unprimeable number, because it can be changed into a prime (2180723) 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, 363618 + ... + 363623.

It is an arithmetic number, because the mean of its divisors is an integer number (727242).

2^2181723 is an apocalyptic number.

2181723 is a deficient number, since it is larger than the sum of its proper divisors (727245).

2181723 is an equidigital number, since it uses as much as digits as its factorization.

2181723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727244.

The product of its digits is 672, while the sum is 24.

The square root of 2181723 is about 1477.0656722028. The cubic root of 2181723 is about 129.6979773700.

The spelling of 2181723 in words is "two million, one hundred eighty-one thousand, seven hundred twenty-three".