21055434401 has 2 divisors, whose sum is σ = 21055434402. Its totient is φ = 21055434400.

The previous prime is 21055434373. The next prime is 21055434403. The reversal of 21055434401 is 10443455012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17226300001 + 3829134400 = 131249^2 + 61880^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21055434401 is a prime.

It is a Sophie Germain prime.

Together with 21055434403, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21055434403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527717200 + 10527717201.

It is an arithmetic number, because the mean of its divisors is an integer number (10527717201).

Almost surely, 2^21055434401 is an apocalyptic number.

It is an amenable number.

21055434401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21055434401 is an equidigital number, since it uses as much as digits as its factorization.

21055434401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9600, while the sum is 29.

Adding to 21055434401 its reverse (10443455012), we get a palindrome (31498889413).

The spelling of 21055434401 in words is "twenty-one billion, fifty-five million, four hundred thirty-four thousand, four hundred one".