1327681721 has 8 divisors (see below), whose sum is σ = 1362352488. Its totient is φ = 1293120000.

The previous prime is 1327681711. The next prime is 1327681723. The reversal of 1327681721 is 1271867231.

It can be written as a sum of positive squares in 4 ways, for example, as 128029225 + 1199652496 = 11315^2 + 34636^2 .

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-1327681721 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 (1327681723) 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, 2300 + ... + 51581.

It is an arithmetic number, because the mean of its divisors is an integer number (170294061).

Almost surely, 2^1327681721 is an apocalyptic number.

It is an amenable number.

1327681721 is a deficient number, since it is larger than the sum of its proper divisors (34670767).

1327681721 is an equidigital number, since it uses as much as digits as its factorization.

1327681721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54523.

The product of its digits is 28224, while the sum is 38.

The square root of 1327681721 is about 36437.3670975278. The cubic root of 1327681721 is about 1099.0851128388.

The spelling of 1327681721 in words is "one billion, three hundred twenty-seven million, six hundred eighty-one thousand, seven hundred twenty-one".