21043660516 has 6 divisors (see below), whose sum is σ = 36826405910. Its totient is φ = 10521830256.

The previous prime is 21043660459. The next prime is 21043660537. The reversal of 21043660516 is 61506634012.

It can be written as a sum of positive squares in only one way, i.e., 16977047616 + 4066612900 = 130296^2 + 63770^2 .

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 2630457561 + ... + 2630457568.

Almost surely, 2^21043660516 is an apocalyptic number.

It is an amenable number.

21043660516 is a deficient number, since it is larger than the sum of its proper divisors (15782745394).

21043660516 is a wasteful number, since it uses less digits than its factorization.

21043660516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5260915133 (or 5260915131 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

The spelling of 21043660516 in words is "twenty-one billion, forty-three million, six hundred sixty thousand, five hundred sixteen".