65621066643891 has 24 divisors (see below), whose sum is σ = 103583983863360. Its totient is φ = 39700693047600.

The previous prime is 65621066643889. The next prime is 65621066643893. The reversal of 65621066643891 is 19834666012656.

It is an interprime number because it is at equal distance from previous prime (65621066643889) and next prime (65621066643893).

It is not a de Polignac number, because 65621066643891 - 2¹ = 65621066643889 is a prime.

It is a super-2 number, since 2×65621066643891² (a number of 28 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (65621066643893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 580362961 + ... + 580476018.

It is an arithmetic number, because the mean of its divisors is an integer number (4315999327640).

Almost surely, 2^{65621066643891} is an apocalyptic number.

65621066643891 is a deficient number, since it is larger than the sum of its proper divisors (37962917219469).

65621066643891 is a wasteful number, since it uses less digits than its factorization.

65621066643891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1160839567 (or 1160839564 counting only the distinct ones).

The product of its (nonzero) digits is 67184640, while the sum is 63.

The spelling of 65621066643891 in words is "sixty-five trillion, six hundred twenty-one billion, sixty-six million, six hundred forty-three thousand, eight hundred ninety-one".