21201220021021 has 16 divisors (see below), whose sum is σ = 23066078515200. Its totient is φ = 19425962844288.

The previous prime is 21201220021019. The next prime is 21201220021027. The reversal of 21201220021021 is 12012002210212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21201220021021 - 2¹ = 21201220021019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201220020986 and 21201220021004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201220021027) 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 15 ways as a sum of consecutive naturals, for example, 125056776 + ... + 125226193.

It is an arithmetic number, because the mean of its divisors is an integer number (1441629907200).

Almost surely, 2^{21201220021021} is an apocalyptic number.

It is an amenable number.

21201220021021 is a deficient number, since it is larger than the sum of its proper divisors (1864858494179).

21201220021021 is a wasteful number, since it uses less digits than its factorization.

21201220021021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250283148.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21201220021021 its reverse (12012002210212), we get a palindrome (33213222231233).

The spelling of 21201220021021 in words is "twenty-one trillion, two hundred one billion, two hundred twenty million, twenty-one thousand, twenty-one".