66443556121 has 4 divisors (see below), whose sum is σ = 66446572212. Its totient is φ = 66440540032.

The previous prime is 66443556079. The next prime is 66443556131. The reversal of 66443556121 is 12165534466.

66443556121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12165534466 = 2 ⋅6082767233.

It can be written as a sum of positive squares in 2 ways, for example, as 46326105225 + 20117450896 = 215235^2 + 141836^2 .

It is a cyclic number.

It is not a de Polignac number, because 66443556121 - 2²⁷ = 66309338393 is a prime.

It is a super-3 number, since 3×66443556121³ (a number of 33 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66443556131) 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, 1474756 + ... + 1519141.

It is an arithmetic number, because the mean of its divisors is an integer number (16611643053).

Almost surely, 2^66443556121 is an apocalyptic number.

It is an amenable number.

66443556121 is a deficient number, since it is larger than the sum of its proper divisors (3016091).

66443556121 is a wasteful number, since it uses less digits than its factorization.

66443556121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3016090.

The product of its digits is 518400, while the sum is 43.

The spelling of 66443556121 in words is "sixty-six billion, four hundred forty-three million, five hundred fifty-six thousand, one hundred twenty-one".