161721867823 has 2 divisors, whose sum is σ = 161721867824. Its totient is φ = 161721867822.

The previous prime is 161721867809. The next prime is 161721867851. The reversal of 161721867823 is 328768127161.

It is a weak prime.

It is an emirp because it is prime and its reverse (328768127161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161721867823 - 2³³ = 153131933231 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161721867863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80860933911 + 80860933912.

It is an arithmetic number, because the mean of its divisors is an integer number (80860933912).

Almost surely, 2^161721867823 is an apocalyptic number.

161721867823 is a deficient number, since it is larger than the sum of its proper divisors (1).

161721867823 is an equidigital number, since it uses as much as digits as its factorization.

161721867823 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1354752, while the sum is 52.

The spelling of 161721867823 in words is "one hundred sixty-one billion, seven hundred twenty-one million, eight hundred sixty-seven thousand, eight hundred twenty-three".