664993720665 has 24 divisors (see below), whose sum is σ = 1152762893568. Its totient is φ = 354630360480.

The previous prime is 664993720663. The next prime is 664993720669. The reversal of 664993720665 is 566027399466.

It is a happy number.

664993720665 is a `hidden beast` number, since 66 + 499 + 3 + 7 + 20 + 6 + 65 = 666.

It is not a de Polignac number, because 664993720665 - 2¹ = 664993720663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (664993720663) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 193071 + ... + 1169300.

It is an arithmetic number, because the mean of its divisors is an integer number (48031787232).

Almost surely, 2^664993720665 is an apocalyptic number.

It is an amenable number.

664993720665 is a deficient number, since it is larger than the sum of its proper divisors (487769172903).

664993720665 is a wasteful number, since it uses less digits than its factorization.

664993720665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1373229 (or 1373226 counting only the distinct ones).

The product of its (nonzero) digits is 88179840, while the sum is 63.

The spelling of 664993720665 in words is "six hundred sixty-four billion, nine hundred ninety-three million, seven hundred twenty thousand, six hundred sixty-five".