21155055013 has 2 divisors, whose sum is σ = 21155055014. Its totient is φ = 21155055012.

The previous prime is 21155055001. The next prime is 21155055079. The reversal of 21155055013 is 31055055112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18047772964 + 3107282049 = 134342^2 + 55743^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21155055013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21155055113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577527506 + 10577527507.

It is an arithmetic number, because the mean of its divisors is an integer number (10577527507).

Almost surely, 2^21155055013 is an apocalyptic number.

It is an amenable number.

21155055013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21155055013 is an equidigital number, since it uses as much as digits as its factorization.

21155055013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3750, while the sum is 28.

Subtracting 21155055013 from its reverse (31055055112), we obtain a palindrome (9900000099).

The spelling of 21155055013 in words is "twenty-one billion, one hundred fifty-five million, fifty-five thousand, thirteen".