21001121120221 has 4 divisors (see below), whose sum is σ = 22910313949344. Its totient is φ = 19091928291100.

The previous prime is 21001121120207. The next prime is 21001121120233. The reversal of 21001121120221 is 12202112110012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21001121120221 - 2¹⁹ = 21001120595933 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001121120195 and 21001121120204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001121120201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 954596414545 + ... + 954596414566.

It is an arithmetic number, because the mean of its divisors is an integer number (5727578487336).

Almost surely, 2^{21001121120221} is an apocalyptic number.

It is an amenable number.

21001121120221 is a deficient number, since it is larger than the sum of its proper divisors (1909192829123).

21001121120221 is a wasteful number, since it uses less digits than its factorization.

21001121120221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1909192829122.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21001121120221 its reverse (12202112110012), we get a palindrome (33203233230233).

The spelling of 21001121120221 in words is "twenty-one trillion, one billion, one hundred twenty-one million, one hundred twenty thousand, two hundred twenty-one".