3665221555 has 4 divisors (see below), whose sum is σ = 4398265872. Its totient is φ = 2932177240.

The previous prime is 3665221537. The next prime is 3665221561. The reversal of 3665221555 is 5551225663.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5551225663 = 10733 ⋅517211.

It is not a de Polignac number, because 3665221555 - 2⁵ = 3665221523 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 366522151 + ... + 366522160.

It is an arithmetic number, because the mean of its divisors is an integer number (1099566468).

Almost surely, 2^3665221555 is an apocalyptic number.

3665221555 is a deficient number, since it is larger than the sum of its proper divisors (733044317).

3665221555 is an equidigital number, since it uses as much as digits as its factorization.

3665221555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 733044316.

The product of its digits is 270000, while the sum is 40.

The square root of 3665221555 is about 60541.0732891316. The cubic root of 3665221555 is about 1541.8190618801.

The spelling of 3665221555 in words is "three billion, six hundred sixty-five million, two hundred twenty-one thousand, five hundred fifty-five".