6665643621 has 48 divisors (see below), whose sum is σ = 11936730624. Its totient is φ = 3490221312.

The previous prime is 6665643617. The next prime is 6665643671. The reversal of 6665643621 is 1263465666.

6665643621 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 6665643621 - 2² = 6665643617 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6665643601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 82500 + ... + 141906.

It is an arithmetic number, because the mean of its divisors is an integer number (248681888).

Almost surely, 2^6665643621 is an apocalyptic number.

It is an amenable number.

6665643621 is a deficient number, since it is larger than the sum of its proper divisors (5271087003).

6665643621 is a wasteful number, since it uses less digits than its factorization.

6665643621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59570 (or 59567 counting only the distinct ones).

The product of its digits is 933120, while the sum is 45.

The square root of 6665643621 is about 81643.3930027409. The cubic root of 6665643621 is about 1881.9757805539.

The spelling of 6665643621 in words is "six billion, six hundred sixty-five million, six hundred forty-three thousand, six hundred twenty-one".