165771021643 has 2 divisors, whose sum is σ = 165771021644. Its totient is φ = 165771021642.

The previous prime is 165771021631. The next prime is 165771021653. The reversal of 165771021643 is 346120177561.

It is a strong prime.

It is an emirp because it is prime and its reverse (346120177561) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165771021643 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 165771021643.

It is not a weakly prime, because it can be changed into another prime (165771021653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82885510821 + 82885510822.

It is an arithmetic number, because the mean of its divisors is an integer number (82885510822).

Almost surely, 2^165771021643 is an apocalyptic number.

165771021643 is a deficient number, since it is larger than the sum of its proper divisors (1).

165771021643 is an equidigital number, since it uses as much as digits as its factorization.

165771021643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 211680, while the sum is 43.

The spelling of 165771021643 in words is "one hundred sixty-five billion, seven hundred seventy-one million, twenty-one thousand, six hundred forty-three".