3865661 has 4 divisors (see below), whose sum is σ = 3938652. Its totient is φ = 3792672.

The previous prime is 3865637. The next prime is 3865663. The reversal of 3865661 is 1665683.

3865661 = 136² + 137² + ... + 241².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1665683 = 23 ⋅72421.

It can be written as a sum of positive squares in 2 ways, for example, as 3367225 + 498436 = 1835^2 + 706^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3865661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3865663) 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, 36416 + ... + 36521.

It is an arithmetic number, because the mean of its divisors is an integer number (984663).

Almost surely, 2^3865661 is an apocalyptic number.

It is an amenable number.

3865661 is a deficient number, since it is larger than the sum of its proper divisors (72991).

3865661 is an equidigital number, since it uses as much as digits as its factorization.

3865661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72990.

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

The square root of 3865661 is about 1966.1284291724. The cubic root of 3865661 is about 156.9427489472.

The spelling of 3865661 in words is "three million, eight hundred sixty-five thousand, six hundred sixty-one".