21011101210021 has 16 divisors (see below), whose sum is σ = 22712085397120. Its totient is φ = 19322252464320.

The previous prime is 21011101210003. The next prime is 21011101210037. The reversal of 21011101210021 is 12001210111012.

It is a happy number.

It is not a de Polignac number, because 21011101210021 - 2¹¹ = 21011101207973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011101209983 and 21011101210010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011101210621) 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, 16908331 + ... + 18108391.

It is an arithmetic number, because the mean of its divisors is an integer number (1419505337320).

Almost surely, 2^{21011101210021} is an apocalyptic number.

It is an amenable number.

21011101210021 is a deficient number, since it is larger than the sum of its proper divisors (1700984187099).

21011101210021 is a wasteful number, since it uses less digits than its factorization.

21011101210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1205116.

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

Adding to 21011101210021 its reverse (12001210111012), we get a palindrome (33012311321033).

The spelling of 21011101210021 in words is "twenty-one trillion, eleven billion, one hundred one million, two hundred ten thousand, twenty-one".