21515500403513 has 2 divisors, whose sum is σ = 21515500403514. Its totient is φ = 21515500403512.

The previous prime is 21515500403497. The next prime is 21515500403569. The reversal of 21515500403513 is 31530400551512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11390172754489 + 10125327649024 = 3374933^2 + 3182032^2 .

It is a cyclic number.

It is not a de Polignac number, because 21515500403513 - 2⁴ = 21515500403497 is a prime.

It is a super-2 number, since 2×21515500403513² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21515500403713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757750201756 + 10757750201757.

It is an arithmetic number, because the mean of its divisors is an integer number (10757750201757).

Almost surely, 2^{21515500403513} is an apocalyptic number.

It is an amenable number.

21515500403513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515500403513 is an equidigital number, since it uses as much as digits as its factorization.

21515500403513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 45000, while the sum is 35.

The spelling of 21515500403513 in words is "twenty-one trillion, five hundred fifteen billion, five hundred million, four hundred three thousand, five hundred thirteen".