66888891 has 6 divisors (see below), whose sum is σ = 96617300. Its totient is φ = 44592588.

The previous prime is 66888889. The next prime is 66888907. The reversal of 66888891 is 19888866.

It is not a de Polignac number, because 66888891 - 2¹ = 66888889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66888821) 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 5 ways as a sum of consecutive naturals, for example, 3716041 + ... + 3716058.

Almost surely, 2^66888891 is an apocalyptic number.

66888891 is a deficient number, since it is larger than the sum of its proper divisors (29728409).

66888891 is a wasteful number, since it uses less digits than its factorization.

66888891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7432105 (or 7432102 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 54.

The square root of 66888891 is about 8178.5628933206. The cubic root of 66888891 is about 405.9301711222.

The spelling of 66888891 in words is "sixty-six million, eight hundred eighty-eight thousand, eight hundred ninety-one".