1209909899381 has 2 divisors, whose sum is σ = 1209909899382. Its totient is φ = 1209909899380.

The previous prime is 1209909899281. The next prime is 1209909899413. The reversal of 1209909899381 is 1839989099021.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1166162412100 + 43747487281 = 1079890^2 + 209159^2 .

It is an emirp because it is prime and its reverse (1839989099021) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1209909899381 - 2¹⁰ = 1209909898357 is a prime.

It is a super-2 number, since 2×1209909899381² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1209909899281) 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, 604954949690 + 604954949691.

It is an arithmetic number, because the mean of its divisors is an integer number (604954949691).

Almost surely, 2^{1209909899381} is an apocalyptic number.

It is an amenable number.

1209909899381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1209909899381 is an equidigital number, since it uses as much as digits as its factorization.

1209909899381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 22674816, while the sum is 68.

The spelling of 1209909899381 in words is "one trillion, two hundred nine billion, nine hundred nine million, eight hundred ninety-nine thousand, three hundred eighty-one".