2661726721 has 8 divisors (see below), whose sum is σ = 2688940800. Its totient is φ = 2634539232.

The previous prime is 2661726719. The next prime is 2661726731. The reversal of 2661726721 is 1276271662.

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 2661726721 - 2¹ = 2661726719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2661726731) 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, 241080 + ... + 251878.

It is an arithmetic number, because the mean of its divisors is an integer number (336117600).

Almost surely, 2^2661726721 is an apocalyptic number.

It is an amenable number.

2661726721 is a deficient number, since it is larger than the sum of its proper divisors (27214079).

2661726721 is a wasteful number, since it uses less digits than its factorization.

2661726721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13295.

The product of its digits is 84672, while the sum is 40.

The square root of 2661726721 is about 51591.9249592414. The cubic root of 2661726721 is about 1385.8657276464.

The spelling of 2661726721 in words is "two billion, six hundred sixty-one million, seven hundred twenty-six thousand, seven hundred twenty-one".