1271661721 has 12 divisors (see below), whose sum is σ = 1402284436. Its totient is φ = 1152328320.

The previous prime is 1271661719. The next prime is 1271661733.

1271661721 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 2 ways, for example, as 339886096 + 931775625 = 18436^2 + 30525^2 .

It is not a de Polignac number, because 1271661721 - 2¹ = 1271661719 is a prime.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1271661121) 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 11 ways as a sum of consecutive naturals, for example, 21085 + ... + 54661.

Almost surely, 2^1271661721 is an apocalyptic number.

1271661721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1271661721 is a deficient number, since it is larger than the sum of its proper divisors (130622715).

1271661721 is a wasteful number, since it uses less digits than its factorization.

1271661721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33912 (or 33901 counting only the distinct ones).

The product of its digits is 7056, while the sum is 34.

The square root of 1271661721 is about 35660.3662488203. The cubic root of 1271661721 is about 1083.4042448468.

The spelling of 1271661721 in words is "one billion, two hundred seventy-one million, six hundred sixty-one thousand, seven hundred twenty-one".