78278869 has 2 divisors, whose sum is σ = 78278870. Its totient is φ = 78278868.

The previous prime is 78278861. The next prime is 78278887. The reversal of 78278869 is 96887287.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72335025 + 5943844 = 8505^2 + 2438^2 .

It is a cyclic number.

It is not a de Polignac number, because 78278869 - 2³ = 78278861 is a prime.

It is a super-2 number, since 2×78278869² = 12255162663838322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78278861) 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, 39139434 + 39139435.

It is an arithmetic number, because the mean of its divisors is an integer number (39139435).

Almost surely, 2^78278869 is an apocalyptic number.

It is an amenable number.

78278869 is a deficient number, since it is larger than the sum of its proper divisors (1).

78278869 is an equidigital number, since it uses as much as digits as its factorization.

78278869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2709504, while the sum is 55.

The square root of 78278869 is about 8847.5346283583. The cubic root of 78278869 is about 427.7744557278.

The spelling of 78278869 in words is "seventy-eight million, two hundred seventy-eight thousand, eight hundred sixty-nine".