3965645221 has 4 divisors (see below), whose sum is σ = 3966128332. Its totient is φ = 3965162112.

The previous prime is 3965645213. The next prime is 3965645227. The reversal of 3965645221 is 1225465693.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1225465693 = 257 ⋅4768349.

It can be written as a sum of positive squares in 2 ways, for example, as 3573050625 + 392594596 = 59775^2 + 19814^2 .

It is a cyclic number.

It is not a de Polignac number, because 3965645221 - 2³ = 3965645213 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 (3965645227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 229026 + ... + 245731.

It is an arithmetic number, because the mean of its divisors is an integer number (991532083).

Almost surely, 2^3965645221 is an apocalyptic number.

It is an amenable number.

3965645221 is a deficient number, since it is larger than the sum of its proper divisors (483111).

3965645221 is an equidigital number, since it uses as much as digits as its factorization.

3965645221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 483110.

The product of its digits is 388800, while the sum is 43.

The square root of 3965645221 is about 62973.3691412489. The cubic root of 3965645221 is about 1582.8434112017.

The spelling of 3965645221 in words is "three billion, nine hundred sixty-five million, six hundred forty-five thousand, two hundred twenty-one".