21123055601 has 2 divisors, whose sum is σ = 21123055602. Its totient is φ = 21123055600.

The previous prime is 21123055589. The next prime is 21123055627. The reversal of 21123055601 is 10655032112.

It is an a-pointer prime, because the next prime (21123055627) can be obtained adding 21123055601 to its sum of digits (26).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21110637025 + 12418576 = 145295^2 + 3524^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123055601 - 2¹⁸ = 21122793457 is a prime.

It is not a weakly prime, because it can be changed into another prime (21123055691) 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 as a sum of consecutive naturals, namely, 10561527800 + 10561527801.

It is an arithmetic number, because the mean of its divisors is an integer number (10561527801).

Almost surely, 2^21123055601 is an apocalyptic number.

It is an amenable number.

21123055601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123055601 is an equidigital number, since it uses as much as digits as its factorization.

21123055601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1800, while the sum is 26.

Adding to 21123055601 its reverse (10655032112), we get a palindrome (31778087713).

The spelling of 21123055601 in words is "twenty-one billion, one hundred twenty-three million, fifty-five thousand, six hundred one".