2121640206409 has 2 divisors, whose sum is σ = 2121640206410. Its totient is φ = 2121640206408.

The previous prime is 2121640206397. The next prime is 2121640206443. The reversal of 2121640206409 is 9046020461212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1123133648400 + 998506558009 = 1059780^2 + 999253^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121640206409 - 2¹⁹ = 2121639682121 is a prime.

It is not a weakly prime, because it can be changed into another prime (2121640201409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060820103204 + 1060820103205.

It is an arithmetic number, because the mean of its divisors is an integer number (1060820103205).

Almost surely, 2^{2121640206409} is an apocalyptic number.

It is an amenable number.

2121640206409 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121640206409 is an equidigital number, since it uses as much as digits as its factorization.

2121640206409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 41472, while the sum is 37.

The spelling of 2121640206409 in words is "two trillion, one hundred twenty-one billion, six hundred forty million, two hundred six thousand, four hundred nine".