16555434121 has 2 divisors, whose sum is σ = 16555434122. Its totient is φ = 16555434120.

The previous prime is 16555434101. The next prime is 16555434127. The reversal of 16555434121 is 12143455561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12322110025 + 4233324096 = 111005^2 + 65064^2 .

It is an emirp because it is prime and its reverse (12143455561) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16555434121 is a prime.

It is not a weakly prime, because it can be changed into another prime (16555434127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8277717060 + 8277717061.

It is an arithmetic number, because the mean of its divisors is an integer number (8277717061).

Almost surely, 2^16555434121 is an apocalyptic number.

It is an amenable number.

16555434121 is a deficient number, since it is larger than the sum of its proper divisors (1).

16555434121 is an equidigital number, since it uses as much as digits as its factorization.

16555434121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72000, while the sum is 37.

Adding to 16555434121 its reverse (12143455561), we get a palindrome (28698889682).

The spelling of 16555434121 in words is "sixteen billion, five hundred fifty-five million, four hundred thirty-four thousand, one hundred twenty-one".