66189881 has 4 divisors (see below), whose sum is σ = 66257664. Its totient is φ = 66122100.

The previous prime is 66189869. The next prime is 66189887. The reversal of 66189881 is 18898166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66189881 - 2⁶ = 66189817 is a prime.

It is a super-2 number, since 2×66189881² = 8762200693588322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66189887) 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, 32405 + ... + 34386.

It is an arithmetic number, because the mean of its divisors is an integer number (16564416).

Almost surely, 2^66189881 is an apocalyptic number.

It is an amenable number.

66189881 is a deficient number, since it is larger than the sum of its proper divisors (67783).

66189881 is an equidigital number, since it uses as much as digits as its factorization.

66189881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67782.

The product of its digits is 165888, while the sum is 47.

The square root of 66189881 is about 8135.7163790290. The cubic root of 66189881 is about 404.5111838708.

The spelling of 66189881 in words is "sixty-six million, one hundred eighty-nine thousand, eight hundred eighty-one".