66191389 has 4 divisors (see below), whose sum is σ = 72208800. Its totient is φ = 60173980.

The previous prime is 66191371. The next prime is 66191393. The reversal of 66191389 is 98319166.

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 66191389 - 2¹⁵ = 66158621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66191399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3008689 + ... + 3008710.

It is an arithmetic number, because the mean of its divisors is an integer number (18052200).

Almost surely, 2^66191389 is an apocalyptic number.

It is an amenable number.

66191389 is a deficient number, since it is larger than the sum of its proper divisors (6017411).

66191389 is a wasteful number, since it uses less digits than its factorization.

66191389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6017410.

The product of its digits is 69984, while the sum is 43.

The square root of 66191389 is about 8135.8090562648. The cubic root of 66191389 is about 404.5142558320.

It can be divided in two parts, 6619 and 1389, that added together give a palindrome (8008).

The spelling of 66191389 in words is "sixty-six million, one hundred ninety-one thousand, three hundred eighty-nine".