2181905 has 8 divisors (see below), whose sum is σ = 2856384. Its totient is φ = 1586800.

The previous prime is 2181889. The next prime is 2181919. The reversal of 2181905 is 5091812.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2181905 - 2⁴ = 2181889 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19781 + ... + 19890.

It is an arithmetic number, because the mean of its divisors is an integer number (357048).

2^2181905 is an apocalyptic number.

It is an amenable number.

2181905 is a deficient number, since it is larger than the sum of its proper divisors (674479).

2181905 is a wasteful number, since it uses less digits than its factorization.

2181905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39687.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 2181905 is about 1477.1272795531. The cubic root of 2181905 is about 129.7015837514.

The spelling of 2181905 in words is "two million, one hundred eighty-one thousand, nine hundred five".