2165981 has 8 divisors (see below), whose sum is σ = 2359200. Its totient is φ = 1980720.

The previous prime is 2165971. The next prime is 2166007. The reversal of 2165981 is 1895612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2165981 is a prime.

It is a super-2 number, since 2×2165981² = 9382947384722, which contains 22 as substring.

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 (2165921) 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, 1415 + ... + 2516.

It is an arithmetic number, because the mean of its divisors is an integer number (294900).

2^2165981 is an apocalyptic number.

It is an amenable number.

2165981 is a deficient number, since it is larger than the sum of its proper divisors (193219).

2165981 is a wasteful number, since it uses less digits than its factorization.

2165981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3979.

The product of its digits is 4320, while the sum is 32.

The square root of 2165981 is about 1471.7272165724. The cubic root of 2165981 is about 129.3852832422.

The spelling of 2165981 in words is "two million, one hundred sixty-five thousand, nine hundred eighty-one".