21002112121 has 8 divisors (see below), whose sum is σ = 21039782400. Its totient is φ = 20964474432.

The previous prime is 21002112119. The next prime is 21002112143. The reversal of 21002112121 is 12121120012.

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 21002112121 - 2¹ = 21002112119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21002112101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1531905 + ... + 1545553.

It is an arithmetic number, because the mean of its divisors is an integer number (2629972800).

Almost surely, 2^21002112121 is an apocalyptic number.

It is an amenable number.

21002112121 is a deficient number, since it is larger than the sum of its proper divisors (37670279).

21002112121 is a wasteful number, since it uses less digits than its factorization.

21002112121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16295.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21002112121 its reverse (12121120012), we get a palindrome (33123232133).

The spelling of 21002112121 in words is "twenty-one billion, two million, one hundred twelve thousand, one hundred twenty-one".