21201120221021 has 12 divisors (see below), whose sum is σ = 22957735455828. Its totient is φ = 19570001053824.

The previous prime is 21201120220979. The next prime is 21201120221023. The reversal of 21201120221021 is 12012202110212.

It can be written as a sum of positive squares in 6 ways, for example, as 1784882640025 + 19416237580996 = 1335995^2 + 4406386^2 .

It is not a de Polignac number, because 21201120221021 - 2⁶ = 21201120220957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201120221023) 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 11 ways as a sum of consecutive naturals, for example, 12337121 + ... + 13950153.

It is an arithmetic number, because the mean of its divisors is an integer number (1913144621319).

Almost surely, 2^{21201120221021} is an apocalyptic number.

It is an amenable number.

21201120221021 is a deficient number, since it is larger than the sum of its proper divisors (1756615234807).

21201120221021 is a wasteful number, since it uses less digits than its factorization.

21201120221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1690832 (or 1690819 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21201120221021 its reverse (12012202110212), we get a palindrome (33213322331233).

The spelling of 21201120221021 in words is "twenty-one trillion, two hundred one billion, one hundred twenty million, two hundred twenty-one thousand, twenty-one".