66199777251 has 4 divisors (see below), whose sum is σ = 88266369672. Its totient is φ = 44133184832.

The previous prime is 66199777247. The next prime is 66199777279. The reversal of 66199777251 is 15277799166.

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 66199777251 - 2² = 66199777247 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66199777351) 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, 11033296206 + ... + 11033296211.

It is an arithmetic number, because the mean of its divisors is an integer number (22066592418).

Almost surely, 2^66199777251 is an apocalyptic number.

66199777251 is a deficient number, since it is larger than the sum of its proper divisors (22066592421).

66199777251 is a wasteful number, since it uses less digits than its factorization.

66199777251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22066592420.

The product of its digits is 10001880, while the sum is 60.

The spelling of 66199777251 in words is "sixty-six billion, one hundred ninety-nine million, seven hundred seventy-seven thousand, two hundred fifty-one".