661775326818 has 8 divisors (see below), whose sum is σ = 1323550653648. Its totient is φ = 220591775604.

The previous prime is 661775326811. The next prime is 661775326843. The reversal of 661775326818 is 818623577166.

It is a sphenic number, since it is the product of 3 distinct primes.

661775326818 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (661775326811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55147943896 + ... + 55147943907.

It is an arithmetic number, because the mean of its divisors is an integer number (165443831706).

Almost surely, 2^661775326818 is an apocalyptic number.

661775326818 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661775326818 is a wasteful number, since it uses less digits than its factorization.

661775326818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110295887808.

The product of its digits is 20321280, while the sum is 60.

The spelling of 661775326818 in words is "six hundred sixty-one billion, seven hundred seventy-five million, three hundred twenty-six thousand, eight hundred eighteen".