1909001372821 has 2 divisors, whose sum is σ = 1909001372822. Its totient is φ = 1909001372820.

The previous prime is 1909001372819. The next prime is 1909001372827. The reversal of 1909001372821 is 1282731009091.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1698554397796 + 210446975025 = 1303286^2 + 458745^2 .

It is a cyclic number.

It is not a de Polignac number, because 1909001372821 - 2¹ = 1909001372819 is a prime.

Together with 1909001372819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1909001372827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 954500686410 + 954500686411.

It is an arithmetic number, because the mean of its divisors is an integer number (954500686411).

Almost surely, 2^{1909001372821} is an apocalyptic number.

It is an amenable number.

1909001372821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1909001372821 is an equidigital number, since it uses as much as digits as its factorization.

1909001372821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54432, while the sum is 43.

It can be divided in two parts, 1909001 and 372821, that added together give a palindrome (2281822).

The spelling of 1909001372821 in words is "one trillion, nine hundred nine billion, one million, three hundred seventy-two thousand, eight hundred twenty-one".