21011211112021 has 4 divisors (see below), whose sum is σ = 22627458120652. Its totient is φ = 19394964103392.

The previous prime is 21011211112019. The next prime is 21011211112063. The reversal of 21011211112021 is 12021111211012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1850552122500 + 19160658989521 = 1360350^2 + 4377289^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011211112021 - 2¹ = 21011211112019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011211111986 and 21011211112004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011211112121) 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, 808123504296 + ... + 808123504321.

It is an arithmetic number, because the mean of its divisors is an integer number (5656864530163).

Almost surely, 2^{21011211112021} is an apocalyptic number.

It is an amenable number.

21011211112021 is a deficient number, since it is larger than the sum of its proper divisors (1616247008631).

21011211112021 is a wasteful number, since it uses less digits than its factorization.

21011211112021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1616247008630.

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

Adding to 21011211112021 its reverse (12021111211012), we get a palindrome (33032322323033).

The spelling of 21011211112021 in words is "twenty-one trillion, eleven billion, two hundred eleven million, one hundred twelve thousand, twenty-one".