2161081 has 4 divisors (see below), whose sum is σ = 2327332. Its totient is φ = 1994832.

The previous prime is 2161031. The next prime is 2161087. The reversal of 2161081 is 1801612.

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 156025 + 2005056 = 395^2 + 1416^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161081 - 2⁷ = 2160953 is a prime.

It is a super-2 number, since 2×2161081² = 9340542177122, which contains 22 as substring.

It is a Duffinian number.

2161081 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2161087) 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, 83106 + ... + 83131.

It is an arithmetic number, because the mean of its divisors is an integer number (581833).

2^2161081 is an apocalyptic number.

It is an amenable number.

2161081 is a deficient number, since it is larger than the sum of its proper divisors (166251).

2161081 is a wasteful number, since it uses less digits than its factorization.

2161081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166250.

The product of its (nonzero) digits is 96, while the sum is 19.

The square root of 2161081 is about 1470.0615633367. The cubic root of 2161081 is about 129.2876421009.

Adding to 2161081 its reverse (1801612), we get a palindrome (3962693).

The spelling of 2161081 in words is "two million, one hundred sixty-one thousand, eighty-one".