6651998991601 has 2 divisors, whose sum is σ = 6651998991602. Its totient is φ = 6651998991600.

The previous prime is 6651998991509. The next prime is 6651998991619. The reversal of 6651998991601 is 1061998991566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3515118768225 + 3136880223376 = 1874865^2 + 1771124^2 .

It is a cyclic number.

It is not a de Polignac number, because 6651998991601 - 2¹⁵ = 6651998958833 is a prime.

It is not a weakly prime, because it can be changed into another prime (6651998991401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3325999495800 + 3325999495801.

It is an arithmetic number, because the mean of its divisors is an integer number (3325999495801).

Almost surely, 2^{6651998991601} is an apocalyptic number.

It is an amenable number.

6651998991601 is a deficient number, since it is larger than the sum of its proper divisors (1).

6651998991601 is an equidigital number, since it uses as much as digits as its factorization.

6651998991601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56687040, while the sum is 70.

The spelling of 6651998991601 in words is "six trillion, six hundred fifty-one billion, nine hundred ninety-eight million, nine hundred ninety-one thousand, six hundred one".