161156721 has 8 divisors (see below), whose sum is σ = 234409824. Its totient is φ = 97670720.

The previous prime is 161156717. The next prime is 161156783. The reversal of 161156721 is 127651161.

161156721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 161156721 - 2² = 161156717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161156621) 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, 2441736 + ... + 2441801.

It is an arithmetic number, because the mean of its divisors is an integer number (29301228).

Almost surely, 2^161156721 is an apocalyptic number.

161156721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

161156721 is a deficient number, since it is larger than the sum of its proper divisors (73253103).

161156721 is a wasteful number, since it uses less digits than its factorization.

161156721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4883551.

The product of its digits is 2520, while the sum is 30.

The square root of 161156721 is about 12694.7517108449. The cubic root of 161156721 is about 544.1886431712.

The spelling of 161156721 in words is "one hundred sixty-one million, one hundred fifty-six thousand, seven hundred twenty-one".