221100100021 has 16 divisors (see below), whose sum is σ = 239352422400. Its totient is φ = 203636291760.

The previous prime is 221100100007. The next prime is 221100100037. The reversal of 221100100021 is 120001001122.

It is a cyclic number.

It is not a de Polignac number, because 221100100021 - 2²⁹ = 220563229109 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221100099980 and 221100100007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221100100051) 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 15 ways as a sum of consecutive naturals, for example, 637255 + ... + 921028.

It is an arithmetic number, because the mean of its divisors is an integer number (14959526400).

Almost surely, 2^221100100021 is an apocalyptic number.

It is an amenable number.

221100100021 is a deficient number, since it is larger than the sum of its proper divisors (18252322379).

221100100021 is a wasteful number, since it uses less digits than its factorization.

221100100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1558536.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 221100100021 its reverse (120001001122), we get a palindrome (341101101143).

The spelling of 221100100021 in words is "two hundred twenty-one billion, one hundred million, one hundred thousand, twenty-one".