2100212120021 has 16 divisors (see below), whose sum is σ = 2249724423600. Its totient is φ = 1953604866048.

The previous prime is 2100212120003. The next prime is 2100212120101. The reversal of 2100212120021 is 1200212120012.

It can be written as a sum of positive squares in 8 ways, for example, as 1031308996 + 2099180811025 = 32114^2 + 1448855^2 .

It is a cyclic number.

It is not a de Polignac number, because 2100212120021 - 2³⁸ = 1825334213077 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2100212119978 and 2100212120005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2100212120521) 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, 3166625 + ... + 3771993.

It is an arithmetic number, because the mean of its divisors is an integer number (140607776475).

Almost surely, 2^{2100212120021} is an apocalyptic number.

It is an amenable number.

2100212120021 is a deficient number, since it is larger than the sum of its proper divisors (149512303579).

2100212120021 is a wasteful number, since it uses less digits than its factorization.

2100212120021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607768.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 2100212120021 its reverse (1200212120012), we get a palindrome (3300424240033).

Subtracting from 2100212120021 its reverse (1200212120012), we obtain a palindrome (900000000009).

The spelling of 2100212120021 in words is "two trillion, one hundred billion, two hundred twelve million, one hundred twenty thousand, twenty-one".