66438191569 has 4 divisors (see below), whose sum is σ = 66441064960. Its totient is φ = 66435318180.

The previous prime is 66438191543. The next prime is 66438191579. The reversal of 66438191569 is 96519183466.

It is a happy number.

66438191569 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 66438191569 - 2³⁵ = 32078453201 is a prime.

It is a super-2 number, since 2×66438191569² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66438191579) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1401729 + ... + 1448350.

It is an arithmetic number, because the mean of its divisors is an integer number (16610266240).

Almost surely, 2^66438191569 is an apocalyptic number.

It is an amenable number.

66438191569 is a deficient number, since it is larger than the sum of its proper divisors (2873391).

66438191569 is a wasteful number, since it uses less digits than its factorization.

66438191569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2873390.

The product of its digits is 8398080, while the sum is 58.

The spelling of 66438191569 in words is "sixty-six billion, four hundred thirty-eight million, one hundred ninety-one thousand, five hundred sixty-nine".