1291878043789 has 4 divisors (see below), whose sum is σ = 1291884776380. Its totient is φ = 1291871311200.

The previous prime is 1291878043763. The next prime is 1291878043793. The reversal of 1291878043789 is 9873408781921.

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 800547141289 + 491330902500 = 894733^2 + 700950^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291878043789 - 2⁷ = 1291878043661 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 (1291878043289) 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, 3069762 + ... + 3465139.

It is an arithmetic number, because the mean of its divisors is an integer number (322971194095).

Almost surely, 2^{1291878043789} is an apocalyptic number.

It is an amenable number.

1291878043789 is a deficient number, since it is larger than the sum of its proper divisors (6732591).

1291878043789 is an equidigital number, since it uses as much as digits as its factorization.

1291878043789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6732590.

The product of its (nonzero) digits is 48771072, while the sum is 67.

The spelling of 1291878043789 in words is "one trillion, two hundred ninety-one billion, eight hundred seventy-eight million, forty-three thousand, seven hundred eighty-nine".