1999377844561 has 4 divisors (see below), whose sum is σ = 2000522309872. Its totient is φ = 1998233379252.

The previous prime is 1999377844559. The next prime is 1999377844571. The reversal of 1999377844561 is 1654487739991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1999377844561 - 2¹ = 1999377844559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1999377844571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 572230035 + ... + 572233528.

It is an arithmetic number, because the mean of its divisors is an integer number (500130577468).

Almost surely, 2^{1999377844561} is an apocalyptic number.

It is an amenable number.

1999377844561 is a deficient number, since it is larger than the sum of its proper divisors (1144465311).

1999377844561 is a wasteful number, since it uses less digits than its factorization.

1999377844561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1144465310.

The product of its digits is 411505920, while the sum is 73.

The spelling of 1999377844561 in words is "one trillion, nine hundred ninety-nine billion, three hundred seventy-seven million, eight hundred forty-four thousand, five hundred sixty-one".