3665571881 has 4 divisors (see below), whose sum is σ = 3665718672. Its totient is φ = 3665425092.

The previous prime is 3665571859. The next prime is 3665571901. The reversal of 3665571881 is 1881755663.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1881755663 = 14929 ⋅126047.

It is a cyclic number.

It is not a de Polignac number, because 3665571881 - 2¹⁸ = 3665309737 is a prime.

It is a super-2 number, since 2×3665571881² = 26872834429555756322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3665571281) 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, 25535 + ... + 89348.

It is an arithmetic number, because the mean of its divisors is an integer number (916429668).

Almost surely, 2^3665571881 is an apocalyptic number.

It is an amenable number.

3665571881 is a deficient number, since it is larger than the sum of its proper divisors (146791).

3665571881 is a wasteful number, since it uses less digits than its factorization.

3665571881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146790.

The product of its digits is 1209600, while the sum is 50.

The square root of 3665571881 is about 60543.9665119490. The cubic root of 3665571881 is about 1541.8681832487.

The spelling of 3665571881 in words is "three billion, six hundred sixty-five million, five hundred seventy-one thousand, eight hundred eighty-one".