21011123121 has 8 divisors (see below), whose sum is σ = 28016050080. Its totient is φ = 14006805792.

The previous prime is 21011123117. The next prime is 21011123171. The reversal of 21011123121 is 12132111012.

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

It is not a de Polignac number, because 21011123121 - 2² = 21011123117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011123121.

It is not an unprimeable number, because it can be changed into a prime (21011123171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64791 + ... + 214988.

It is an arithmetic number, because the mean of its divisors is an integer number (3502006260).

Almost surely, 2^21011123121 is an apocalyptic number.

It is an amenable number.

21011123121 is a deficient number, since it is larger than the sum of its proper divisors (7004926959).

21011123121 is a wasteful number, since it uses less digits than its factorization.

21011123121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304815.

The product of its (nonzero) digits is 24, while the sum is 15.

Adding to 21011123121 its reverse (12132111012), we get a palindrome (33143234133).

The spelling of 21011123121 in words is "twenty-one billion, eleven million, one hundred twenty-three thousand, one hundred twenty-one".