2123681 has 8 divisors (see below), whose sum is σ = 2461824. Its totient is φ = 1794240.

The previous prime is 2123669. The next prime is 2123683. The reversal of 2123681 is 1863212.

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

It is not a de Polignac number, because 2123681 - 2⁶ = 2123617 is a prime.

It is a super-2 number, since 2×2123681² = 9020041979522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2123683) 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, 1640 + ... + 2633.

It is an arithmetic number, because the mean of its divisors is an integer number (307728).

2^2123681 is an apocalyptic number.

It is an amenable number.

2123681 is a deficient number, since it is larger than the sum of its proper divisors (338143).

2123681 is an equidigital number, since it uses as much as digits as its factorization.

2123681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4351.

The product of its digits is 576, while the sum is 23.

The square root of 2123681 is about 1457.2854902180. The cubic root of 2123681 is about 128.5374738672.

Adding to 2123681 its reverse (1863212), we get a palindrome (3986893).

The spelling of 2123681 in words is "two million, one hundred twenty-three thousand, six hundred eighty-one".