66643642 has 8 divisors (see below), whose sum is σ = 107655156. Its totient is φ = 30758592.

The previous prime is 66643637. The next prime is 66643649. The reversal of 66643642 is 24634666.

It can be written as a sum of positive squares in 2 ways, for example, as 64144081 + 2499561 = 8009^2 + 1581^2 .

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

It is not an unprimeable number, because it can be changed into a prime (66643649) 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 3 ways as a sum of consecutive naturals, for example, 1281583 + ... + 1281634.

Almost surely, 2^66643642 is an apocalyptic number.

66643642 is a deficient number, since it is larger than the sum of its proper divisors (41011514).

66643642 is a wasteful number, since it uses less digits than its factorization.

66643642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2563232.

The product of its digits is 124416, while the sum is 37.

The square root of 66643642 is about 8163.5557203954. Note that the first 3 decimals coincide. The cubic root of 66643642 is about 405.4334474387.

The spelling of 66643642 in words is "sixty-six million, six hundred forty-three thousand, six hundred forty-two".