78191913 has 8 divisors (see below), whose sum is σ = 105212800. Its totient is φ = 51649488.

The previous prime is 78191899. The next prime is 78191921. The reversal of 78191913 is 31919187.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78191913 - 2⁶ = 78191849 is a prime.

It is a super-2 number, since 2×78191913² = 12227950517199138, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (78191923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 119233 + ... + 119886.

It is an arithmetic number, because the mean of its divisors is an integer number (13151600).

Almost surely, 2^78191913 is an apocalyptic number.

It is an amenable number.

78191913 is a deficient number, since it is larger than the sum of its proper divisors (27020887).

78191913 is a wasteful number, since it uses less digits than its factorization.

78191913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239231.

The product of its digits is 13608, while the sum is 39.

The square root of 78191913 is about 8842.6191255759. The cubic root of 78191913 is about 427.6159994369.

The spelling of 78191913 in words is "seventy-eight million, one hundred ninety-one thousand, nine hundred thirteen".