1909967688661 has 4 divisors (see below), whose sum is σ = 1921007964492. Its totient is φ = 1898927412832.

The previous prime is 1909967688623. The next prime is 1909967688697. The reversal of 1909967688661 is 1668867699091.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 902291012100 + 1007676676561 = 949890^2 + 1003831^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1909967688661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1909967688061) 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 in 3 ways as a sum of consecutive naturals, for example, 5520137656 + ... + 5520138001.

It is an arithmetic number, because the mean of its divisors is an integer number (480251991123).

Almost surely, 2^{1909967688661} is an apocalyptic number.

It is an amenable number.

1909967688661 is a deficient number, since it is larger than the sum of its proper divisors (11040275831).

1909967688661 is a wasteful number, since it uses less digits than its factorization.

1909967688661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11040275830.

The product of its (nonzero) digits is 423263232, while the sum is 76.

The spelling of 1909967688661 in words is "one trillion, nine hundred nine billion, nine hundred sixty-seven million, six hundred eighty-eight thousand, six hundred sixty-one".