66443661 has 24 divisors (see below), whose sum is σ = 98167680. Its totient is φ = 43295616.

The previous prime is 66443653. The next prime is 66443677. The reversal of 66443661 is 16634466.

66443661 is a `hidden beast` number, since 6 + 644 + 3 + 6 + 6 + 1 = 666.

It is not a de Polignac number, because 66443661 - 2³ = 66443653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66443681) 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 23 ways as a sum of consecutive naturals, for example, 79930 + ... + 80756.

It is an arithmetic number, because the mean of its divisors is an integer number (4090320).

Almost surely, 2^66443661 is an apocalyptic number.

It is an amenable number.

66443661 is a deficient number, since it is larger than the sum of its proper divisors (31724019).

66443661 is a wasteful number, since it uses less digits than its factorization.

66443661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1025 (or 1022 counting only the distinct ones).

The product of its digits is 62208, while the sum is 36.

The square root of 66443661 is about 8151.2981174780. The cubic root of 66443661 is about 405.0275061337.

The spelling of 66443661 in words is "sixty-six million, four hundred forty-three thousand, six hundred sixty-one".