21002121112121 has 16 divisors (see below), whose sum is σ = 21958432062336. Its totient is φ = 20049443246976.

The previous prime is 21002121112109. The next prime is 21002121112183. The reversal of 21002121112121 is 12121112120012.

It is a cyclic number.

It is not a de Polignac number, because 21002121112121 - 2⁴² = 16604074601017 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21002121112121.

It is not an unprimeable number, because it can be changed into a prime (21002123112121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25967981 + ... + 26764533.

It is an arithmetic number, because the mean of its divisors is an integer number (1372402003896).

Almost surely, 2^{21002121112121} is an apocalyptic number.

It is an amenable number.

21002121112121 is a deficient number, since it is larger than the sum of its proper divisors (956310950215).

21002121112121 is a wasteful number, since it uses less digits than its factorization.

21002121112121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 798832.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21002121112121 its reverse (12121112120012), we get a palindrome (33123233232133).

The spelling of 21002121112121 in words is "twenty-one trillion, two billion, one hundred twenty-one million, one hundred twelve thousand, one hundred twenty-one".