21981179529 has 12 divisors (see below), whose sum is σ = 31778730100. Its totient is φ = 14641133184.

The previous prime is 21981179527. The next prime is 21981179533. The reversal of 21981179529 is 92597118912.

It is a happy number.

21981179529 is a `hidden beast` number, since 21 + 9 + 81 + 17 + 9 + 529 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 7098399504 + 14882780025 = 84252^2 + 121995^2 .

It is not a de Polignac number, because 21981179529 - 2¹ = 21981179527 is a prime.

It is a super-2 number, since 2×21981179529² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21981179527) 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 11 ways as a sum of consecutive naturals, for example, 1071484 + ... + 1091805.

Almost surely, 2^21981179529 is an apocalyptic number.

It is an amenable number.

21981179529 is a deficient number, since it is larger than the sum of its proper divisors (9797550571).

21981179529 is a wasteful number, since it uses less digits than its factorization.

21981179529 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2164424 (or 2164421 counting only the distinct ones).

The product of its digits is 816480, while the sum is 54.

The spelling of 21981179529 in words is "twenty-one billion, nine hundred eighty-one million, one hundred seventy-nine thousand, five hundred twenty-nine".