1978309085779 has 4 divisors (see below), whose sum is σ = 2130486707776. Its totient is φ = 1826131463784.

The previous prime is 1978309085723. The next prime is 1978309085843. The reversal of 1978309085779 is 9775809038791.

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

It is a cyclic number.

It is not a de Polignac number, because 1978309085779 - 2¹⁷ = 1978308954707 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1978309095779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76088810979 + ... + 76088811004.

It is an arithmetic number, because the mean of its divisors is an integer number (532621676944).

Almost surely, 2^{1978309085779} is an apocalyptic number.

1978309085779 is a deficient number, since it is larger than the sum of its proper divisors (152177621997).

1978309085779 is a wasteful number, since it uses less digits than its factorization.

1978309085779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152177621996.

The product of its (nonzero) digits is 240045120, while the sum is 73.

The spelling of 1978309085779 in words is "one trillion, nine hundred seventy-eight billion, three hundred nine million, eighty-five thousand, seven hundred seventy-nine".