664817680726 has 16 divisors (see below), whose sum is σ = 1011736535040. Its totient is φ = 327576470760.

The previous prime is 664817680699. The next prime is 664817680727. The reversal of 664817680726 is 627086718466.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664817680727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 764886 + ... + 1383721.

It is an arithmetic number, because the mean of its divisors is an integer number (63233533440).

Almost surely, 2^664817680726 is an apocalyptic number.

664817680726 is a deficient number, since it is larger than the sum of its proper divisors (346918854314).

664817680726 is a wasteful number, since it uses less digits than its factorization.

664817680726 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2150859.

The product of its (nonzero) digits is 32514048, while the sum is 61.

The spelling of 664817680726 in words is "six hundred sixty-four billion, eight hundred seventeen million, six hundred eighty thousand, seven hundred twenty-six".