66204178687 has 4 divisors (see below), whose sum is σ = 66207239176. Its totient is φ = 66201118200.

The previous prime is 66204178639. The next prime is 66204178723. The reversal of 66204178687 is 78687140266.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66204178687 - 2¹⁹ = 66203654399 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 (66204178487) 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, 1497564 + ... + 1541137.

It is an arithmetic number, because the mean of its divisors is an integer number (16551809794).

Almost surely, 2^66204178687 is an apocalyptic number.

66204178687 is a deficient number, since it is larger than the sum of its proper divisors (3060489).

66204178687 is a wasteful number, since it uses less digits than its factorization.

66204178687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3060488.

The product of its (nonzero) digits is 5419008, while the sum is 55.

The spelling of 66204178687 in words is "sixty-six billion, two hundred four million, one hundred seventy-eight thousand, six hundred eighty-seven".