21071968616 has 8 divisors (see below), whose sum is σ = 39509941170. Its totient is φ = 10535984304.

The previous prime is 21071968597. The next prime is 21071968637. The reversal of 21071968616 is 61686917012.

It can be written as a sum of positive squares in only one way, i.e., 12133022500 + 8938946116 = 110150^2 + 94546^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21071968616² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1316998031 + ... + 1316998046.

Almost surely, 2^21071968616 is an apocalyptic number.

It is an amenable number.

21071968616 is a deficient number, since it is larger than the sum of its proper divisors (18437972554).

21071968616 is a wasteful number, since it uses less digits than its factorization.

21071968616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2633996083 (or 2633996079 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 47.

The spelling of 21071968616 in words is "twenty-one billion, seventy-one million, nine hundred sixty-eight thousand, six hundred sixteen".