16513912781 has 2 divisors, whose sum is σ = 16513912782. Its totient is φ = 16513912780.

The previous prime is 16513912771. The next prime is 16513912823. The reversal of 16513912781 is 18721931561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13696957156 + 2816955625 = 117034^2 + 53075^2 .

It is a cyclic number.

It is not a de Polignac number, because 16513912781 - 2⁶ = 16513912717 is a prime.

It is a super-2 number, since 2×16513912781² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16513912711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8256956390 + 8256956391.

It is an arithmetic number, because the mean of its divisors is an integer number (8256956391).

Almost surely, 2^16513912781 is an apocalyptic number.

It is an amenable number.

16513912781 is a deficient number, since it is larger than the sum of its proper divisors (1).

16513912781 is an equidigital number, since it uses as much as digits as its factorization.

16513912781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 44.

The spelling of 16513912781 in words is "sixteen billion, five hundred thirteen million, nine hundred twelve thousand, seven hundred eighty-one".