11667171721 has 2 divisors, whose sum is σ = 11667171722. Its totient is φ = 11667171720.

The previous prime is 11667171709. The next prime is 11667171767. The reversal of 11667171721 is 12717176611.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11586369600 + 80802121 = 107640^2 + 8989^2 .

It is an emirp because it is prime and its reverse (12717176611) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11667171721 is a prime.

It is a super-2 number, since 2×11667171721² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (11667171421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5833585860 + 5833585861.

It is an arithmetic number, because the mean of its divisors is an integer number (5833585861).

Almost surely, 2^11667171721 is an apocalyptic number.

It is an amenable number.

11667171721 is a deficient number, since it is larger than the sum of its proper divisors (1).

11667171721 is an equidigital number, since it uses as much as digits as its factorization.

11667171721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24696, while the sum is 40.

The spelling of 11667171721 in words is "eleven billion, six hundred sixty-seven million, one hundred seventy-one thousand, seven hundred twenty-one".