2181663 has 12 divisors (see below), whose sum is σ = 3437928. Its totient is φ = 1322160.

The previous prime is 2181659. The next prime is 2181671. The reversal of 2181663 is 3661812.

It is not a de Polignac number, because 2181663 - 2² = 2181659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181463) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10920 + ... + 11117.

It is an arithmetic number, because the mean of its divisors is an integer number (286494).

2^2181663 is an apocalyptic number.

2181663 is a deficient number, since it is larger than the sum of its proper divisors (1256265).

2181663 is a wasteful number, since it uses less digits than its factorization.

2181663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22054 (or 22051 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 2181663 is about 1477.0453615241. The cubic root of 2181663 is about 129.6967884091.

It can be divided in two parts, 218 and 1663, that added together give a palindrome (1881).

The spelling of 2181663 in words is "two million, one hundred eighty-one thousand, six hundred sixty-three".