2102221211821 has 2 divisors, whose sum is σ = 2102221211822. Its totient is φ = 2102221211820.

The previous prime is 2102221211809. The next prime is 2102221211891. The reversal of 2102221211821 is 1281121222012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1695948825796 + 406272386025 = 1302286^2 + 637395^2 .

It is a cyclic number.

It is not a de Polignac number, because 2102221211821 - 2¹³ = 2102221203629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2102221211891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1051110605910 + 1051110605911.

It is an arithmetic number, because the mean of its divisors is an integer number (1051110605911).

Almost surely, 2^{2102221211821} is an apocalyptic number.

It is an amenable number.

2102221211821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2102221211821 is an equidigital number, since it uses as much as digits as its factorization.

2102221211821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 512, while the sum is 25.

Adding to 2102221211821 its reverse (1281121222012), we get a palindrome (3383342433833).

The spelling of 2102221211821 in words is "two trillion, one hundred two billion, two hundred twenty-one million, two hundred eleven thousand, eight hundred twenty-one".