21521171212 has 24 divisors (see below), whose sum is σ = 38741410400. Its totient is φ = 10453121280.

The previous prime is 21521171201. The next prime is 21521171227. The reversal of 21521171212 is 21217112512.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21837 + ... + 208612.

Almost surely, 2^21521171212 is an apocalyptic number.

It is an amenable number.

21521171212 is a deficient number, since it is larger than the sum of its proper divisors (17220239188).

21521171212 is a wasteful number, since it uses less digits than its factorization.

21521171212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231121 (or 231119 counting only the distinct ones).

The product of its digits is 560, while the sum is 25.

Adding to 21521171212 its reverse (21217112512), we get a palindrome (42738283724).

The spelling of 21521171212 in words is "twenty-one billion, five hundred twenty-one million, one hundred seventy-one thousand, two hundred twelve".