1991928947329 has 4 divisors (see below), whose sum is σ = 1991946668976. Its totient is φ = 1991911225684.

The previous prime is 1991928947243. The next prime is 1991928947353. The reversal of 1991928947329 is 9237498291991.

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 1991928947329 - 2⁹ = 1991928946817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991928947429) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8691139 + ... + 8917384.

It is an arithmetic number, because the mean of its divisors is an integer number (497986667244).

Almost surely, 2^{1991928947329} is an apocalyptic number.

It is an amenable number.

1991928947329 is a deficient number, since it is larger than the sum of its proper divisors (17721647).

1991928947329 is a wasteful number, since it uses less digits than its factorization.

1991928947329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17721646.

The product of its digits is 158723712, while the sum is 73.

The spelling of 1991928947329 in words is "one trillion, nine hundred ninety-one billion, nine hundred twenty-eight million, nine hundred forty-seven thousand, three hundred twenty-nine".