78691991041 has 4 divisors (see below), whose sum is σ = 82833674800. Its totient is φ = 74550307284.

The previous prime is 78691991017. The next prime is 78691991047. The reversal of 78691991041 is 14019919687.

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, and also an emirpimes, since its reverse is a distinct semiprime: 14019919687 = 211 ⋅66445117.

It is a cyclic number.

It is not a de Polignac number, because 78691991041 - 2¹³ = 78691982849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78691991047) 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, 2070841851 + ... + 2070841888.

It is an arithmetic number, because the mean of its divisors is an integer number (20708418700).

Almost surely, 2^78691991041 is an apocalyptic number.

It is an amenable number.

78691991041 is a deficient number, since it is larger than the sum of its proper divisors (4141683759).

78691991041 is a wasteful number, since it uses less digits than its factorization.

78691991041 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4141683758.

The product of its (nonzero) digits is 979776, while the sum is 55.

The spelling of 78691991041 in words is "seventy-eight billion, six hundred ninety-one million, nine hundred ninety-one thousand, forty-one".