161716721 has 8 divisors (see below), whose sum is σ = 162821760. Its totient is φ = 160615728.

The previous prime is 161716717. The next prime is 161716729. The reversal of 161716721 is 127617161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161716721 - 2² = 161716717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161716729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 130115 + ... + 131351.

It is an arithmetic number, because the mean of its divisors is an integer number (20352720).

Almost surely, 2^161716721 is an apocalyptic number.

It is an amenable number.

161716721 is a deficient number, since it is larger than the sum of its proper divisors (1105039).

161716721 is a wasteful number, since it uses less digits than its factorization.

161716721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2023.

The product of its digits is 3528, while the sum is 32.

The square root of 161716721 is about 12716.7889421819. The cubic root of 161716721 is about 544.8182442483.

The spelling of 161716721 in words is "one hundred sixty-one million, seven hundred sixteen thousand, seven hundred twenty-one".