161080721 has 8 divisors (see below), whose sum is σ = 166033704. Its totient is φ = 156159360.

The previous prime is 161080669. The next prime is 161080723. The reversal of 161080721 is 127080161.

161080721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 27447121 + 133633600 = 5239^2 + 11560^2 .

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 161080721 - 2⁶ = 161080657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161080723) 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, 2651 + ... + 18143.

It is an arithmetic number, because the mean of its divisors is an integer number (20754213).

Almost surely, 2^161080721 is an apocalyptic number.

It is an amenable number.

161080721 is a deficient number, since it is larger than the sum of its proper divisors (4952983).

161080721 is a wasteful number, since it uses less digits than its factorization.

161080721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15811.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 161080721 is about 12691.7579948563. The cubic root of 161080721 is about 544.1030849648.

The spelling of 161080721 in words is "one hundred sixty-one million, eighty thousand, seven hundred twenty-one".