21620134642321 has 16 divisors (see below), whose sum is σ = 21968348600320. Its totient is φ = 21273347208960.

The previous prime is 21620134642229. The next prime is 21620134642343. The reversal of 21620134642321 is 12324643102612.

It is a cyclic number.

It is not a de Polignac number, because 21620134642321 - 2²⁷ = 21620000424593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21620134646321) 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 in 15 ways as a sum of consecutive naturals, for example, 163216765 + ... + 163349173.

It is an arithmetic number, because the mean of its divisors is an integer number (1373021787520).

Almost surely, 2^{21620134642321} is an apocalyptic number.

It is an amenable number.

21620134642321 is a deficient number, since it is larger than the sum of its proper divisors (348213957999).

21620134642321 is a wasteful number, since it uses less digits than its factorization.

21620134642321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137776.

The product of its (nonzero) digits is 82944, while the sum is 37.

Adding to 21620134642321 its reverse (12324643102612), we get a palindrome (33944777744933).

The spelling of 21620134642321 in words is "twenty-one trillion, six hundred twenty billion, one hundred thirty-four million, six hundred forty-two thousand, three hundred twenty-one".