21541123234957 has 2 divisors, whose sum is σ = 21541123234958. Its totient is φ = 21541123234956.

The previous prime is 21541123234921. The next prime is 21541123235069. The reversal of 21541123234957 is 75943232114512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12180791029801 + 9360332205156 = 3490099^2 + 3059466^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21541123234957 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21541123234957.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21541123334957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770561617478 + 10770561617479.

It is an arithmetic number, because the mean of its divisors is an integer number (10770561617479).

Almost surely, 2^{21541123234957} is an apocalyptic number.

It is an amenable number.

21541123234957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21541123234957 is an equidigital number, since it uses as much as digits as its factorization.

21541123234957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1814400, while the sum is 49.

The spelling of 21541123234957 in words is "twenty-one trillion, five hundred forty-one billion, one hundred twenty-three million, two hundred thirty-four thousand, nine hundred fifty-seven".