78828091 has 2 divisors, whose sum is σ = 78828092. Its totient is φ = 78828090.

The previous prime is 78828089. The next prime is 78828097. The reversal of 78828091 is 19082887.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78828091 - 2¹ = 78828089 is a prime.

Together with 78828089, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (78828097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39414045 + 39414046.

It is an arithmetic number, because the mean of its divisors is an integer number (39414046).

Almost surely, 2^78828091 is an apocalyptic number.

78828091 is a deficient number, since it is larger than the sum of its proper divisors (1).

78828091 is an equidigital number, since it uses as much as digits as its factorization.

78828091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64512, while the sum is 43.

The square root of 78828091 is about 8878.5185138062. The cubic root of 78828091 is about 428.7725786600.

The spelling of 78828091 in words is "seventy-eight million, eight hundred twenty-eight thousand, ninety-one".