78912989 has 2 divisors, whose sum is σ = 78912990. Its totient is φ = 78912988.

The previous prime is 78912983. The next prime is 78912991. The reversal of 78912989 is 98921987.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72812089 + 6100900 = 8533^2 + 2470^2 .

It is a cyclic number.

It is not a de Polignac number, because 78912989 - 2¹⁶ = 78847453 is a prime.

Together with 78912991, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78912989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78912983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39456494 + 39456495.

It is an arithmetic number, because the mean of its divisors is an integer number (39456495).

Almost surely, 2^78912989 is an apocalyptic number.

It is an amenable number.

78912989 is a deficient number, since it is larger than the sum of its proper divisors (1).

78912989 is an equidigital number, since it uses as much as digits as its factorization.

78912989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 653184, while the sum is 53.

The square root of 78912989 is about 8883.2983176296. The cubic root of 78912989 is about 428.9264530527.

The spelling of 78912989 in words is "seventy-eight million, nine hundred twelve thousand, nine hundred eighty-nine".