646627656401 has 8 divisors (see below), whose sum is σ = 650935525800. Its totient is φ = 642322182528.

The previous prime is 646627656379. The next prime is 646627656419. The reversal of 646627656401 is 104656726646.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 46388544400 + 600239112001 = 215380^2 + 774751^2 .

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-646627656401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646627656601) 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, 55586 + ... + 1138571.

It is an arithmetic number, because the mean of its divisors is an integer number (81366940725).

Almost surely, 2^646627656401 is an apocalyptic number.

It is an amenable number.

646627656401 is a deficient number, since it is larger than the sum of its proper divisors (4307869399).

646627656401 is a wasteful number, since it uses less digits than its factorization.

646627656401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1197763.

The product of its (nonzero) digits is 8709120, while the sum is 53.

The spelling of 646627656401 in words is "six hundred forty-six billion, six hundred twenty-seven million, six hundred fifty-six thousand, four hundred one".