2166778513 has 2 divisors, whose sum is σ = 2166778514. Its totient is φ = 2166778512.

The previous prime is 2166778507. The next prime is 2166778543. The reversal of 2166778513 is 3158776612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2139247504 + 27531009 = 46252^2 + 5247^2 .

It is a cyclic number.

It is not a de Polignac number, because 2166778513 - 2⁹ = 2166778001 is a prime.

It is not a weakly prime, because it can be changed into another prime (2166778543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1083389256 + 1083389257.

It is an arithmetic number, because the mean of its divisors is an integer number (1083389257).

Almost surely, 2^2166778513 is an apocalyptic number.

It is an amenable number.

2166778513 is a deficient number, since it is larger than the sum of its proper divisors (1).

2166778513 is an equidigital number, since it uses as much as digits as its factorization.

2166778513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 423360, while the sum is 46.

The square root of 2166778513 is about 46548.6682194024. The cubic root of 2166778513 is about 1294.0116115668.

The spelling of 2166778513 in words is "two billion, one hundred sixty-six million, seven hundred seventy-eight thousand, five hundred thirteen".