21210233121 has 96 divisors (see below), whose sum is σ = 41594342400. Its totient is φ = 10078266240.

The previous prime is 21210233117. The next prime is 21210233129. The reversal of 21210233121 is 12133201212.

21210233121 is a `hidden beast` number, since 212 + 102 + 331 + 21 = 666.

It is not a de Polignac number, because 21210233121 - 2² = 21210233117 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21210233094 and 21210233103.

It is not an unprimeable number, because it can be changed into a prime (21210233129) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 354070 + ... + 409616.

It is an arithmetic number, because the mean of its divisors is an integer number (433274400).

Almost surely, 2^21210233121 is an apocalyptic number.

21210233121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21210233121 is a deficient number, since it is larger than the sum of its proper divisors (20384109279).

21210233121 is a wasteful number, since it uses less digits than its factorization.

21210233121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55619 (or 55616 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21210233121 its reverse (12133201212), we get a palindrome (33343434333).

The spelling of 21210233121 in words is "twenty-one billion, two hundred ten million, two hundred thirty-three thousand, one hundred twenty-one".