2181181801 has 4 divisors (see below), whose sum is σ = 2181563604. Its totient is φ = 2180800000.

The previous prime is 2181181799. The next prime is 2181181813. The reversal of 2181181801 is 1081811812.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1856317225 + 324864576 = 43085^2 + 18024^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181181801 - 2¹ = 2181181799 is a prime.

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 a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2181181601) 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, 182200 + ... + 193801.

It is an arithmetic number, because the mean of its divisors is an integer number (545390901).

Almost surely, 2^2181181801 is an apocalyptic number.

It is an amenable number.

2181181801 is a deficient number, since it is larger than the sum of its proper divisors (381803).

2181181801 is an equidigital number, since it uses as much as digits as its factorization.

2181181801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 381802.

The product of its (nonzero) digits is 1024, while the sum is 31.

The square root of 2181181801 is about 46703.1241032118. The cubic root of 2181181801 is about 1296.8725217399.

The spelling of 2181181801 in words is "two billion, one hundred eighty-one million, one hundred eighty-one thousand, eight hundred one".