1978990741729 has 2 divisors, whose sum is σ = 1978990741730. Its totient is φ = 1978990741728.

The previous prime is 1978990741727. The next prime is 1978990741753. The reversal of 1978990741729 is 9271470998791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1972766320704 + 6224421025 = 1404552^2 + 78895^2 .

It is a cyclic number.

It is not a de Polignac number, because 1978990741729 - 2¹ = 1978990741727 is a prime.

Together with 1978990741727, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1978990741723) 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 as a sum of consecutive naturals, namely, 989495370864 + 989495370865.

It is an arithmetic number, because the mean of its divisors is an integer number (989495370865).

Almost surely, 2^{1978990741729} is an apocalyptic number.

It is an amenable number.

1978990741729 is a deficient number, since it is larger than the sum of its proper divisors (1).

1978990741729 is an equidigital number, since it uses as much as digits as its factorization.

1978990741729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144027072, while the sum is 73.

The spelling of 1978990741729 in words is "one trillion, nine hundred seventy-eight billion, nine hundred ninety million, seven hundred forty-one thousand, seven hundred twenty-nine".