78017993 has 4 divisors (see below), whose sum is σ = 78171780. Its totient is φ = 77864208.

The previous prime is 78017969. The next prime is 78017999. The reversal of 78017993 is 39971087.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 39971087 = 13 ⋅3074699.

It can be written as a sum of positive squares in 2 ways, for example, as 54125449 + 23892544 = 7357^2 + 4888^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78017993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78017999) 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, 76130 + ... + 77147.

It is an arithmetic number, because the mean of its divisors is an integer number (19542945).

Almost surely, 2^78017993 is an apocalyptic number.

It is an amenable number.

78017993 is a deficient number, since it is larger than the sum of its proper divisors (153787).

78017993 is a wasteful number, since it uses less digits than its factorization.

78017993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153786.

The product of its (nonzero) digits is 95256, while the sum is 44.

The square root of 78017993 is about 8832.7794606228. The cubic root of 78017993 is about 427.2987194677.

The spelling of 78017993 in words is "seventy-eight million, seventeen thousand, nine hundred ninety-three".