65121355621 has 16 divisors (see below), whose sum is σ = 76834078720. Its totient is φ = 54011467440.

The previous prime is 65121355591. The next prime is 65121355631. The reversal of 65121355621 is 12655312156.

It is a happy number.

It is not a de Polignac number, because 65121355621 - 2³¹ = 62973871973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65121355631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3536380 + ... + 3554746.

It is an arithmetic number, because the mean of its divisors is an integer number (4802129920).

Almost surely, 2^65121355621 is an apocalyptic number.

It is an amenable number.

65121355621 is a deficient number, since it is larger than the sum of its proper divisors (11712723099).

65121355621 is a wasteful number, since it uses less digits than its factorization.

65121355621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34744.

The product of its digits is 54000, while the sum is 37.

Adding to 65121355621 its reverse (12655312156), we get a palindrome (77776667777).

The spelling of 65121355621 in words is "sixty-five billion, one hundred twenty-one million, three hundred fifty-five thousand, six hundred twenty-one".