161721867845 has 16 divisors (see below), whose sum is σ = 204313380480. Its totient is φ = 122548276800.

The previous prime is 161721867823. The next prime is 161721867851. The reversal of 161721867845 is 548768127161.

It is not a de Polignac number, because 161721867845 - 2¹² = 161721863749 is a prime.

It is a congruent number.

It is an unprimeable number.

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, 464675 + ... + 734415.

It is an arithmetic number, because the mean of its divisors is an integer number (12769586280).

Almost surely, 2^161721867845 is an apocalyptic number.

It is an amenable number.

161721867845 is a deficient number, since it is larger than the sum of its proper divisors (42591512635).

161721867845 is a wasteful number, since it uses less digits than its factorization.

161721867845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276076.

The product of its digits is 4515840, while the sum is 56.

The spelling of 161721867845 in words is "one hundred sixty-one billion, seven hundred twenty-one million, eight hundred sixty-seven thousand, eight hundred forty-five".