3666685745721 has 8 divisors (see below), whose sum is σ = 4888930032544. Its totient is φ = 2444449311360.

The previous prime is 3666685745699. The next prime is 3666685745731. The reversal of 3666685745721 is 1275475866663.

It is a happy number.

3666685745721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 3666685745721 - 2³⁴ = 3649505876537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3666685745731) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 769975 + ... + 2815356.

It is an arithmetic number, because the mean of its divisors is an integer number (611116254068).

Almost surely, 2^{3666685745721} is an apocalyptic number.

It is an amenable number.

3666685745721 is a deficient number, since it is larger than the sum of its proper divisors (1222244286823).

3666685745721 is a wasteful number, since it uses less digits than its factorization.

3666685745721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3926231.

The product of its digits is 304819200, while the sum is 66.

The spelling of 3666685745721 in words is "three trillion, six hundred sixty-six billion, six hundred eighty-five million, seven hundred forty-five thousand, seven hundred twenty-one".