2185681 has 4 divisors (see below), whose sum is σ = 2200500. Its totient is φ = 2170864.

The previous prime is 2185661. The next prime is 2185697. The reversal of 2185681 is 1865812.

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 781456 + 1404225 = 884^2 + 1185^2 .

It is a cyclic number.

It is not a de Polignac number, because 2185681 - 2⁵ = 2185649 is a prime.

It is a super-2 number, since 2×2185681² = 9554402867522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2185661) 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, 7186 + ... + 7483.

It is an arithmetic number, because the mean of its divisors is an integer number (550125).

2^2185681 is an apocalyptic number.

It is an amenable number.

2185681 is a deficient number, since it is larger than the sum of its proper divisors (14819).

2185681 is a wasteful number, since it uses less digits than its factorization.

2185681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14818.

The product of its digits is 3840, while the sum is 31.

The square root of 2185681 is about 1478.4048836499. The cubic root of 2185681 is about 129.7763610568.

The spelling of 2185681 in words is "two million, one hundred eighty-five thousand, six hundred eighty-one".