21200000121 has 24 divisors (see below), whose sum is σ = 31128027840. Its totient is φ = 13900840800.

The previous prime is 21200000113. The next prime is 21200000141. The reversal of 21200000121 is 12100000212.

It is not a de Polignac number, because 21200000121 - 2³ = 21200000113 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21200000141) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 228151 + ... + 307331.

It is an arithmetic number, because the mean of its divisors is an integer number (1297001160).

Almost surely, 2^21200000121 is an apocalyptic number.

It is an amenable number.

21200000121 is a deficient number, since it is larger than the sum of its proper divisors (9928027719).

21200000121 is a wasteful number, since it uses less digits than its factorization.

21200000121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79677 (or 79674 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21200000121 its reverse (12100000212), we get a palindrome (33300000333).

Subtracting from 21200000121 its reverse (12100000212), we obtain a palindrome (9099999909).

The spelling of 21200000121 in words is "twenty-one billion, two hundred million, one hundred twenty-one", and thus it is an aban number.