161721867843 has 16 divisors (see below), whose sum is σ = 239602742400. Its totient is φ = 107807923080.

The previous prime is 161721867823. The next prime is 161721867851. The reversal of 161721867843 is 348768127161.

161721867843 is a `hidden beast` number, since 1 + 617 + 2 + 18 + 6 + 7 + 8 + 4 + 3 = 666.

It is not a de Polignac number, because 161721867843 - 2⁶ = 161721867779 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161721867843.

It is not an unprimeable number, because it can be changed into a prime (161721867823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 282048 + ... + 634818.

It is an arithmetic number, because the mean of its divisors is an integer number (14975171400).

Almost surely, 2^161721867843 is an apocalyptic number.

161721867843 is a deficient number, since it is larger than the sum of its proper divisors (77880874557).

161721867843 is a wasteful number, since it uses less digits than its factorization.

161721867843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 369759 (or 369753 counting only the distinct ones).

The product of its digits is 2709504, while the sum is 54.

The spelling of 161721867843 in words is "one hundred sixty-one billion, seven hundred twenty-one million, eight hundred sixty-seven thousand, eight hundred forty-three".