21100120000021 has 16 divisors (see below), whose sum is σ = 22565170782000. Its totient is φ = 19660248834048.

The previous prime is 21100120000019. The next prime is 21100120000027. The reversal of 21100120000021 is 12000002100112.

It can be written as a sum of positive squares in 8 ways, for example, as 2337578019396 + 18762541980625 = 1528914^2 + 4331575^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100120000021 - 2¹ = 21100120000019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21100119999962 and 21100120000007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100120000027) 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, 2561796 + ... + 6983053.

It is an arithmetic number, because the mean of its divisors is an integer number (1410323173875).

Almost surely, 2^{21100120000021} is an apocalyptic number.

It is an amenable number.

21100120000021 is a deficient number, since it is larger than the sum of its proper divisors (1465050781979).

21100120000021 is a wasteful number, since it uses less digits than its factorization.

21100120000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9546168.

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

Adding to 21100120000021 its reverse (12000002100112), we get a palindrome (33100122100133).

The spelling of 21100120000021 in words is "twenty-one trillion, one hundred billion, one hundred twenty million, twenty-one", and thus it is an aban number.