78120689 has 2 divisors, whose sum is σ = 78120690. Its totient is φ = 78120688.

The previous prime is 78120683. The next prime is 78120701. The reversal of 78120689 is 98602187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69222400 + 8898289 = 8320^2 + 2983^2 .

It is an emirp because it is prime and its reverse (98602187) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78120689 is a prime.

It is a super-2 number, since 2×78120689² = 12205684099669442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78120683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39060344 + 39060345.

It is an arithmetic number, because the mean of its divisors is an integer number (39060345).

Almost surely, 2^78120689 is an apocalyptic number.

It is an amenable number.

78120689 is a deficient number, since it is larger than the sum of its proper divisors (1).

78120689 is an equidigital number, since it uses as much as digits as its factorization.

78120689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 78120689 is about 8838.5908944809. The cubic root of 78120689 is about 427.4861233711.

The spelling of 78120689 in words is "seventy-eight million, one hundred twenty thousand, six hundred eighty-nine".