664944721186 has 4 divisors (see below), whose sum is σ = 997417081782. Its totient is φ = 332472360592.

The previous prime is 664944721183. The next prime is 664944721249. The reversal of 664944721186 is 681127449466.

It is a happy number.

664944721186 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 681127449466 = 2 ⋅340563724733.

It can be written as a sum of positive squares in only one way, i.e., 423190581961 + 241754139225 = 650531^2 + 491685^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 664944721186.

It is not an unprimeable number, because it can be changed into a prime (664944721183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166236180295 + ... + 166236180298.

Almost surely, 2^664944721186 is an apocalyptic number.

664944721186 is a deficient number, since it is larger than the sum of its proper divisors (332472360596).

664944721186 is a wasteful number, since it uses less digits than its factorization.

664944721186 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332472360595.

The product of its digits is 13934592, while the sum is 58.

The spelling of 664944721186 in words is "six hundred sixty-four billion, nine hundred forty-four million, seven hundred twenty-one thousand, one hundred eighty-six".