5515121021581 has 2 divisors, whose sum is σ = 5515121021582. Its totient is φ = 5515121021580.

The previous prime is 5515121021567. The next prime is 5515121021611. The reversal of 5515121021581 is 1851201215155.

5515121021581 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3994166128681 + 1520954892900 = 1998541^2 + 1233270^2 .

It is a cyclic number.

It is not a de Polignac number, because 5515121021581 - 2⁵ = 5515121021549 is a prime.

It is a super-2 number, since 2×5515121021581² (a number of 26 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 5515121021581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (5515121021551) 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, 2757560510790 + 2757560510791.

It is an arithmetic number, because the mean of its divisors is an integer number (2757560510791).

Almost surely, 2^{5515121021581} is an apocalyptic number.

It is an amenable number.

5515121021581 is a deficient number, since it is larger than the sum of its proper divisors (1).

5515121021581 is an equidigital number, since it uses as much as digits as its factorization.

5515121021581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20000, while the sum is 37.

The spelling of 5515121021581 in words is "five trillion, five hundred fifteen billion, one hundred twenty-one million, twenty-one thousand, five hundred eighty-one".