71684172121 has 3 divisors (see below), whose sum is σ = 71684439861. Its totient is φ = 71683904382.

The previous prime is 71684172113. The next prime is 71684172137. The reversal of 71684172121 is 12127148617.

It is a happy number.

The square root of 71684172121 is 267739.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12127148617 = 311 ⋅38994047.

It is not a de Polignac number, because 71684172121 - 2³ = 71684172113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71684172101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 133870 + ... + 401608.

It is an arithmetic number, because the mean of its divisors is an integer number (23894813287).

Almost surely, 2^71684172121 is an apocalyptic number.

71684172121 is the 267739-th square number.

71684172121 is the 133870-th centered octagonal number.

It is an amenable number.

71684172121 is a deficient number, since it is larger than the sum of its proper divisors (267740).

71684172121 is an frugal number, since it uses more digits than its factorization.

71684172121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535478 (or 267739 counting only the distinct ones).

The product of its digits is 37632, while the sum is 40.

The spelling of 71684172121 in words is "seventy-one billion, six hundred eighty-four million, one hundred seventy-two thousand, one hundred twenty-one".