21121111212 has 24 divisors (see below), whose sum is σ = 49285048512. Its totient is φ = 7040019600.

The previous prime is 21121111153. The next prime is 21121111279. The reversal of 21121111212 is 21211112112.

It is a happy number.

It is a super-2 number, since 2×21121111212² (a number of 21 digits) contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21121111191 and 21121111200.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 344787 + ... + 401397.

It is an arithmetic number, because the mean of its divisors is an integer number (2053543688).

Almost surely, 2^21121111212 is an apocalyptic number.

It is an amenable number.

21121111212 is an abundant number, since it is smaller than the sum of its proper divisors (28163937300).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21121111212 is a wasteful number, since it uses less digits than its factorization.

21121111212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87709 (or 87707 counting only the distinct ones).

The product of its digits is 16, while the sum is 15.

Adding to 21121111212 its reverse (21211112112), we get a palindrome (42332223324).

The spelling of 21121111212 in words is "twenty-one billion, one hundred twenty-one million, one hundred eleven thousand, two hundred twelve".