2165981671391 has 2 divisors, whose sum is σ = 2165981671392. Its totient is φ = 2165981671390.

The previous prime is 2165981671361. The next prime is 2165981671417. The reversal of 2165981671391 is 1931761895612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2165981671391 - 2¹⁰ = 2165981670367 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2165981671391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2165981671331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1082990835695 + 1082990835696.

It is an arithmetic number, because the mean of its divisors is an integer number (1082990835696).

Almost surely, 2^{2165981671391} is an apocalyptic number.

2165981671391 is a deficient number, since it is larger than the sum of its proper divisors (1).

2165981671391 is an equidigital number, since it uses as much as digits as its factorization.

2165981671391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4898880, while the sum is 59.

The spelling of 2165981671391 in words is "two trillion, one hundred sixty-five billion, nine hundred eighty-one million, six hundred seventy-one thousand, three hundred ninety-one".