21105950857513 has 2 divisors, whose sum is σ = 21105950857514. Its totient is φ = 21105950857512.

The previous prime is 21105950857469. The next prime is 21105950857553. The reversal of 21105950857513 is 31575805950112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10650739021209 + 10455211836304 = 3263547^2 + 3233452^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21105950857513 is a prime.

It is a super-2 number, since 2×21105950857513² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21105950857553) 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, 10552975428756 + 10552975428757.

It is an arithmetic number, because the mean of its divisors is an integer number (10552975428757).

Almost surely, 2^{21105950857513} is an apocalyptic number.

It is an amenable number.

21105950857513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21105950857513 is an equidigital number, since it uses as much as digits as its factorization.

21105950857513 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1890000, while the sum is 52.

The spelling of 21105950857513 in words is "twenty-one trillion, one hundred five billion, nine hundred fifty million, eight hundred fifty-seven thousand, five hundred thirteen".