1212100100021 has 4 divisors (see below), whose sum is σ = 1212230765772. Its totient is φ = 1211969434272.

The previous prime is 1212100100009. The next prime is 1212100100051. The reversal of 1212100100021 is 1200010012121.

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 427787943025 + 784312156996 = 654055^2 + 885614^2 .

It is a cyclic number.

It is not a de Polignac number, because 1212100100021 - 2¹⁰ = 1212100098997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1212100099975 and 1212100100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212100100051) 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, 65318960 + ... + 65337513.

It is an arithmetic number, because the mean of its divisors is an integer number (303057691443).

Almost surely, 2^{1212100100021} is an apocalyptic number.

It is an amenable number.

1212100100021 is a deficient number, since it is larger than the sum of its proper divisors (130665751).

1212100100021 is an equidigital number, since it uses as much as digits as its factorization.

1212100100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130665750.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 1212100100021 its reverse (1200010012121), we get a palindrome (2412110112142).

The spelling of 1212100100021 in words is "one trillion, two hundred twelve billion, one hundred million, one hundred thousand, twenty-one".