21210200111021 has 4 divisors (see below), whose sum is σ = 21210210418332. Its totient is φ = 21210189803712.

The previous prime is 21210200110973. The next prime is 21210200111053. The reversal of 21210200111021 is 12011100201212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 12689347208521 + 8520852902500 = 3562211^2 + 2919050^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210200111021 - 2¹⁰ = 21210200109997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210200110987 and 21210200111005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210200101021) 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, 892670 + ... + 6573983.

It is an arithmetic number, because the mean of its divisors is an integer number (5302552604583).

Almost surely, 2^{21210200111021} is an apocalyptic number.

It is an amenable number.

21210200111021 is a deficient number, since it is larger than the sum of its proper divisors (10307311).

21210200111021 is an equidigital number, since it uses as much as digits as its factorization.

21210200111021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10307310.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21210200111021 its reverse (12011100201212), we get a palindrome (33221300312233).

The spelling of 21210200111021 in words is "twenty-one trillion, two hundred ten billion, two hundred million, one hundred eleven thousand, twenty-one".