66688822778797 has 4 divisors (see below), whose sum is σ = 66742997290816. Its totient is φ = 66634648266780.

The previous prime is 66688822778779. The next prime is 66688822778827. The reversal of 66688822778797 is 79787722888666.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-66688822778797 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 (66688822778597) 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, 27087254163 + ... + 27087256624.

It is an arithmetic number, because the mean of its divisors is an integer number (16685749322704).

Almost surely, 2^{66688822778797} is an apocalyptic number.

It is an amenable number.

66688822778797 is a deficient number, since it is larger than the sum of its proper divisors (54174512019).

66688822778797 is a wasteful number, since it uses less digits than its factorization.

66688822778797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54174512018.

The product of its digits is 76473040896, while the sum is 91.

The spelling of 66688822778797 in words is "sixty-six trillion, six hundred eighty-eight billion, eight hundred twenty-two million, seven hundred seventy-eight thousand, seven hundred ninety-seven".