21665243312 has 20 divisors (see below), whose sum is σ = 42567628176. Its totient is φ = 10680048960.

The previous prime is 21665243311. The next prime is 21665243351. The reversal of 21665243312 is 21334256612.

It is not an unprimeable number, because it can be changed into a prime (21665243311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9534623 + ... + 9536894.

Almost surely, 2^21665243312 is an apocalyptic number.

It is an amenable number.

21665243312 is a deficient number, since it is larger than the sum of its proper divisors (20902384864).

21665243312 is a wasteful number, since it uses less digits than its factorization.

21665243312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19071596 (or 19071590 counting only the distinct ones).

The product of its digits is 51840, while the sum is 35.

Adding to 21665243312 its reverse (21334256612), we get a palindrome (42999499924).

The spelling of 21665243312 in words is "twenty-one billion, six hundred sixty-five million, two hundred forty-three thousand, three hundred twelve".