3665681 has 4 divisors (see below), whose sum is σ = 3672612. Its totient is φ = 3658752.

The previous prime is 3665677. The next prime is 3665731. The reversal of 3665681 is 1865663.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1865663 = 229 ⋅8147.

It can be written as a sum of positive squares in 2 ways, for example, as 2958400 + 707281 = 1720^2 + 841^2 .

It is a cyclic number.

It is not a de Polignac number, because 3665681 - 2² = 3665677 is a prime.

It is a super-2 number, since 2×3665681² = 26874434387522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3665581) 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, 2600 + ... + 3753.

It is an arithmetic number, because the mean of its divisors is an integer number (918153).

Almost surely, 2^3665681 is an apocalyptic number.

It is an amenable number.

3665681 is a deficient number, since it is larger than the sum of its proper divisors (6931).

3665681 is an equidigital number, since it uses as much as digits as its factorization.

3665681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6930.

The product of its digits is 25920, while the sum is 35.

The square root of 3665681 is about 1914.5968243993. The cubic root of 3665681 is about 154.1883482857.

The spelling of 3665681 in words is "three million, six hundred sixty-five thousand, six hundred eighty-one".