66691471993 has 4 divisors (see below), whose sum is σ = 66713922448. Its totient is φ = 66669021540.

The previous prime is 66691471969. The next prime is 66691472011. The reversal of 66691471993 is 39917419666.

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 66691471993 - 2⁵ = 66691471961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66691471193) 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, 11220771 + ... + 11226712.

It is an arithmetic number, because the mean of its divisors is an integer number (16678480612).

Almost surely, 2^66691471993 is an apocalyptic number.

It is an amenable number.

66691471993 is a deficient number, since it is larger than the sum of its proper divisors (22450455).

66691471993 is a wasteful number, since it uses less digits than its factorization.

66691471993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22450454.

The product of its digits is 13226976, while the sum is 61.

The spelling of 66691471993 in words is "sixty-six billion, six hundred ninety-one million, four hundred seventy-one thousand, nine hundred ninety-three".