2166681 has 8 divisors (see below), whose sum is σ = 3151584. Its totient is φ = 1313120.

The previous prime is 2166679. The next prime is 2166691. The reversal of 2166681 is 1866612.

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 2166681 - 2¹ = 2166679 is a prime.

It is a super-2 number, since 2×2166681² = 9389013111522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2166601) 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, 32796 + ... + 32861.

It is an arithmetic number, because the mean of its divisors is an integer number (393948).

2^2166681 is an apocalyptic number.

It is an amenable number.

2166681 is a deficient number, since it is larger than the sum of its proper divisors (984903).

2166681 is a wasteful number, since it uses less digits than its factorization.

2166681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65671.

The product of its digits is 3456, while the sum is 30.

The square root of 2166681 is about 1471.9650131712. The cubic root of 2166681 is about 129.3992199515.

It can be divided in two parts, 21 and 66681, that multiplied together give a triangular number (1400301 = T₁₆₇₃).

The spelling of 2166681 in words is "two million, one hundred sixty-six thousand, six hundred eighty-one".