21021002112221 has 16 divisors (see below), whose sum is σ = 22357991240640. Its totient is φ = 19695200405760.

The previous prime is 21021002112211. The next prime is 21021002112233. The reversal of 21021002112221 is 12221120012012.

It is a cyclic number.

It is not a de Polignac number, because 21021002112221 - 2²⁶ = 21020935003357 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21021002112221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021002112211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26498066 + ... + 27279836.

It is an arithmetic number, because the mean of its divisors is an integer number (1397374452540).

Almost surely, 2^{21021002112221} is an apocalyptic number.

It is an amenable number.

21021002112221 is a deficient number, since it is larger than the sum of its proper divisors (1336989128419).

21021002112221 is a wasteful number, since it uses less digits than its factorization.

21021002112221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 788924.

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

Adding to 21021002112221 its reverse (12221120012012), we get a palindrome (33242122124233).

The spelling of 21021002112221 in words is "twenty-one trillion, twenty-one billion, two million, one hundred twelve thousand, two hundred twenty-one".