2165138616491 has 2 divisors, whose sum is σ = 2165138616492. Its totient is φ = 2165138616490.

The previous prime is 2165138616467. The next prime is 2165138616517. The reversal of 2165138616491 is 1946168315612.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2165138616491 is a prime.

It is not a weakly prime, because it can be changed into another prime (2165138616401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1082569308245 + 1082569308246.

It is an arithmetic number, because the mean of its divisors is an integer number (1082569308246).

Almost surely, 2^{2165138616491} is an apocalyptic number.

2165138616491 is a deficient number, since it is larger than the sum of its proper divisors (1).

2165138616491 is an equidigital number, since it uses as much as digits as its factorization.

2165138616491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1866240, while the sum is 53.

The spelling of 2165138616491 in words is "two trillion, one hundred sixty-five billion, one hundred thirty-eight million, six hundred sixteen thousand, four hundred ninety-one".