656638566679 has 4 divisors (see below), whose sum is σ = 656975133760. Its totient is φ = 656301999600.

The previous prime is 656638566641. The next prime is 656638566791. The reversal of 656638566679 is 976665836656.

It is a happy number.

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 656638566679 - 2⁹ = 656638566167 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 (656638566179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 168280614 + ... + 168284515.

It is an arithmetic number, because the mean of its divisors is an integer number (164243783440).

Almost surely, 2^656638566679 is an apocalyptic number.

656638566679 is a deficient number, since it is larger than the sum of its proper divisors (336567081).

656638566679 is a wasteful number, since it uses less digits than its factorization.

656638566679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336567080.

The product of its digits is 1763596800, while the sum is 73.

The spelling of 656638566679 in words is "six hundred fifty-six billion, six hundred thirty-eight million, five hundred sixty-six thousand, six hundred seventy-nine".