78997891 has 16 divisors (see below), whose sum is σ = 92240640. Its totient is φ = 66258720.

The previous prime is 78997883. The next prime is 78997949. The reversal of 78997891 is 19879987.

It is a cyclic number.

It is not a de Polignac number, because 78997891 - 2³ = 78997883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78997871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 83481 + ... + 84421.

It is an arithmetic number, because the mean of its divisors is an integer number (5765040).

Almost surely, 2^78997891 is an apocalyptic number.

78997891 is a deficient number, since it is larger than the sum of its proper divisors (13242749).

78997891 is a wasteful number, since it uses less digits than its factorization.

78997891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1194.

The product of its digits is 2286144, while the sum is 58.

The square root of 78997891 is about 8888.0757760046. The cubic root of 78997891 is about 429.0802243638.

The spelling of 78997891 in words is "seventy-eight million, nine hundred ninety-seven thousand, eight hundred ninety-one".