2161661 has 8 divisors (see below), whose sum is σ = 2256384. Its totient is φ = 2068560.

The previous prime is 2161639. The next prime is 2161697. The reversal of 2161661 is 1661612.

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

It is a cyclic number.

It is not a de Polignac number, because 2161661 - 2¹⁴ = 2145277 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2167661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2855 + ... + 3531.

It is an arithmetic number, because the mean of its divisors is an integer number (282048).

2^2161661 is an apocalyptic number.

It is an amenable number.

2161661 is a deficient number, since it is larger than the sum of its proper divisors (94723).

2161661 is a wasteful number, since it uses less digits than its factorization.

2161661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811.

The product of its digits is 432, while the sum is 23.

The square root of 2161661 is about 1470.2588207523. The cubic root of 2161661 is about 129.2992073199.

The spelling of 2161661 in words is "two million, one hundred sixty-one thousand, six hundred sixty-one".