2181838 has 4 divisors (see below), whose sum is σ = 3272760. Its totient is φ = 1090918.

The previous prime is 2181833. The next prime is 2181857. The reversal of 2181838 is 8381812.

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

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 545458 + ... + 545461.

It is an arithmetic number, because the mean of its divisors is an integer number (818190).

2^2181838 is an apocalyptic number.

2181838 is a deficient number, since it is larger than the sum of its proper divisors (1090922).

2181838 is a wasteful number, since it uses less digits than its factorization.

2181838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1090921.

The product of its digits is 3072, while the sum is 31.

The square root of 2181838 is about 1477.1046002230. The cubic root of 2181838 is about 129.7002561508.

The spelling of 2181838 in words is "two million, one hundred eighty-one thousand, eight hundred thirty-eight".