21000101111221 has 16 divisors (see below), whose sum is σ = 22462432706560. Its totient is φ = 19598791408560.

The previous prime is 21000101111207. The next prime is 21000101111237. The reversal of 21000101111221 is 12211110100012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21000101111221 - 2⁵ = 21000101111189 is a prime.

It is a super-2 number, since 2×21000101111221² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000101111921) 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, 99603645 + ... + 99814258.

It is an arithmetic number, because the mean of its divisors is an integer number (1403902044160).

Almost surely, 2^{21000101111221} is an apocalyptic number.

It is an amenable number.

21000101111221 is a deficient number, since it is larger than the sum of its proper divisors (1462331595339).

21000101111221 is a wasteful number, since it uses less digits than its factorization.

21000101111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199418056.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21000101111221 its reverse (12211110100012), we get a palindrome (33211211211233).

The spelling of 21000101111221 in words is "twenty-one trillion, one hundred one million, one hundred eleven thousand, two hundred twenty-one".