2121008012861 has 2 divisors, whose sum is σ = 2121008012862. Its totient is φ = 2121008012860.

The previous prime is 2121008012843. The next prime is 2121008012909. The reversal of 2121008012861 is 1682108001212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1572528540025 + 548479472836 = 1254005^2 + 740594^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121008012861 - 2¹⁴ = 2121007996477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2121008018861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060504006430 + 1060504006431.

It is an arithmetic number, because the mean of its divisors is an integer number (1060504006431).

Almost surely, 2^{2121008012861} is an apocalyptic number.

It is an amenable number.

2121008012861 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121008012861 is an equidigital number, since it uses as much as digits as its factorization.

2121008012861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3072, while the sum is 32.

The spelling of 2121008012861 in words is "two trillion, one hundred twenty-one billion, eight million, twelve thousand, eight hundred sixty-one".