78538891 has 2 divisors, whose sum is σ = 78538892. Its totient is φ = 78538890.

The previous prime is 78538849. The next prime is 78538919. The reversal of 78538891 is 19883587.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78538891 - 2⁹ = 78538379 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78538091) 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 as a sum of consecutive naturals, namely, 39269445 + 39269446.

It is an arithmetic number, because the mean of its divisors is an integer number (39269446).

Almost surely, 2^78538891 is an apocalyptic number.

78538891 is a deficient number, since it is larger than the sum of its proper divisors (1).

78538891 is an equidigital number, since it uses as much as digits as its factorization.

78538891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 483840, while the sum is 49.

The square root of 78538891 is about 8862.2170476693. The cubic root of 78538891 is about 428.2475839928.

The spelling of 78538891 in words is "seventy-eight million, five hundred thirty-eight thousand, eight hundred ninety-one".