21202120020021 has 32 divisors (see below), whose sum is σ = 28690329507840. Its totient is φ = 13925817561600.

The previous prime is 21202120019999. The next prime is 21202120020061. The reversal of 21202120020021 is 12002002120212.

It is not a de Polignac number, because 21202120020021 - 2¹⁸ = 21202119757877 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202120020061) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 542192556 + ... + 542231658.

It is an arithmetic number, because the mean of its divisors is an integer number (896572797120).

Almost surely, 2^{21202120020021} is an apocalyptic number.

It is an amenable number.

21202120020021 is a deficient number, since it is larger than the sum of its proper divisors (7488209487819).

21202120020021 is a wasteful number, since it uses less digits than its factorization.

21202120020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48557.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21202120020021 its reverse (12002002120212), we get a palindrome (33204122140233).

The spelling of 21202120020021 in words is "twenty-one trillion, two hundred two billion, one hundred twenty million, twenty thousand, twenty-one".