721776161 has 8 divisors (see below), whose sum is σ = 760159200. Its totient is φ = 683432640.

The previous prime is 721776119. The next prime is 721776163. The reversal of 721776161 is 161677127.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721776161 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (721776163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32270 + ... + 49848.

It is an arithmetic number, because the mean of its divisors is an integer number (95019900).

Almost surely, 2^721776161 is an apocalyptic number.

It is an amenable number.

721776161 is a deficient number, since it is larger than the sum of its proper divisors (38383039).

721776161 is a wasteful number, since it uses less digits than its factorization.

721776161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19759.

The product of its digits is 24696, while the sum is 38.

The square root of 721776161 is about 26865.8921497128. The cubic root of 721776161 is about 897.0173530206.

The spelling of 721776161 in words is "seven hundred twenty-one million, seven hundred seventy-six thousand, one hundred sixty-one".