667651636721 has 8 divisors (see below), whose sum is σ = 668676729600. Its totient is φ = 666627127632.

The previous prime is 667651636697. The next prime is 667651636823. The reversal of 667651636721 is 127636156766.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-667651636721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (667651636021) 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, 2171255 + ... + 2459603.

It is an arithmetic number, because the mean of its divisors is an integer number (83584591200).

Almost surely, 2^667651636721 is an apocalyptic number.

It is an amenable number.

667651636721 is a deficient number, since it is larger than the sum of its proper divisors (1025092879).

667651636721 is a wasteful number, since it uses less digits than its factorization.

667651636721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291895.

The product of its digits is 11430720, while the sum is 56.

The spelling of 667651636721 in words is "six hundred sixty-seven billion, six hundred fifty-one million, six hundred thirty-six thousand, seven hundred twenty-one".