21131203121 has 8 divisors (see below), whose sum is σ = 24152689344. Its totient is φ = 18110402640.

The previous prime is 21131203117. The next prime is 21131203213. The reversal of 21131203121 is 12130213112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21131203121 - 2² = 21131203117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21131203121.

It is not an unprimeable number, because it can be changed into a prime (21131203021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103610 + ... + 230211.

It is an arithmetic number, because the mean of its divisors is an integer number (3019086168).

Almost surely, 2^21131203121 is an apocalyptic number.

It is an amenable number.

21131203121 is a deficient number, since it is larger than the sum of its proper divisors (3021486223).

21131203121 is an equidigital number, since it uses as much as digits as its factorization.

21131203121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342871.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21131203121 its reverse (12130213112), we get a palindrome (33261416233).

Subtracting from 21131203121 its reverse (12130213112), we obtain a palindrome (9000990009).

The spelling of 21131203121 in words is "twenty-one billion, one hundred thirty-one million, two hundred three thousand, one hundred twenty-one".