21012120120021 has 16 divisors (see below), whose sum is σ = 28188132029568. Its totient is φ = 13922119208000.

The previous prime is 21012120120001. The next prime is 21012120120067. The reversal of 21012120120021 is 12002102121012.

It is a cyclic number.

It is not a de Polignac number, because 21012120120021 - 2³⁰ = 21011046378197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012120120001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 227791 + ... + 6486611.

It is an arithmetic number, because the mean of its divisors is an integer number (1761758251848).

Almost surely, 2^{21012120120021} is an apocalyptic number.

It is an amenable number.

21012120120021 is a deficient number, since it is larger than the sum of its proper divisors (7176011909547).

21012120120021 is a wasteful number, since it uses less digits than its factorization.

21012120120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6265692.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21012120120021 its reverse (12002102121012), we get a palindrome (33014222241033).

The spelling of 21012120120021 in words is "twenty-one trillion, twelve billion, one hundred twenty million, one hundred twenty thousand, twenty-one".