66605890 has 16 divisors (see below), whose sum is σ = 129113208. Its totient is φ = 24592896.

The previous prime is 66605879. The next prime is 66605899. The reversal of 66605890 is 9850666.

66605890 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 49885969 + 16719921 = 7063^2 + 4089^2 .

It is not an unprimeable number, because it can be changed into a prime (66605899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 256047 + ... + 256306.

Almost surely, 2^66605890 is an apocalyptic number.

66605890 is a deficient number, since it is larger than the sum of its proper divisors (62507318).

66605890 is a wasteful number, since it uses less digits than its factorization.

66605890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512373.

The product of its (nonzero) digits is 77760, while the sum is 40.

The square root of 66605890 is about 8161.2431651066. The cubic root of 66605890 is about 405.3568769207.

The spelling of 66605890 in words is "sixty-six million, six hundred five thousand, eight hundred ninety".