21434222155561 has 2 divisors, whose sum is σ = 21434222155562. Its totient is φ = 21434222155560.

The previous prime is 21434222155523. The next prime is 21434222155571. The reversal of 21434222155561 is 16555122243412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14234359394025 + 7199862761536 = 3772845^2 + 2683256^2 .

It is a cyclic number.

It is not a de Polignac number, because 21434222155561 - 2²¹ = 21434220058409 is a prime.

It is not a weakly prime, because it can be changed into another prime (21434222155571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10717111077780 + 10717111077781.

It is an arithmetic number, because the mean of its divisors is an integer number (10717111077781).

Almost surely, 2^{21434222155561} is an apocalyptic number.

It is an amenable number.

21434222155561 is a deficient number, since it is larger than the sum of its proper divisors (1).

21434222155561 is an equidigital number, since it uses as much as digits as its factorization.

21434222155561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576000, while the sum is 43.

Adding to 21434222155561 its reverse (16555122243412), we get a palindrome (37989344398973).

The spelling of 21434222155561 in words is "twenty-one trillion, four hundred thirty-four billion, two hundred twenty-two million, one hundred fifty-five thousand, five hundred sixty-one".