78404399 has 2 divisors, whose sum is σ = 78404400. Its totient is φ = 78404398.

The previous prime is 78404383. The next prime is 78404411. The reversal of 78404399 is 99340487.

It is a strong prime.

It is an emirp because it is prime and its reverse (99340487) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78404399 - 2⁴ = 78404383 is a prime.

It is a super-2 number, since 2×78404399² = 12294499565102402, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78404099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39202199 + 39202200.

It is an arithmetic number, because the mean of its divisors is an integer number (39202200).

Almost surely, 2^78404399 is an apocalyptic number.

78404399 is a deficient number, since it is larger than the sum of its proper divisors (1).

78404399 is an equidigital number, since it uses as much as digits as its factorization.

78404399 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 217728, while the sum is 44.

The square root of 78404399 is about 8854.6258531911. The cubic root of 78404399 is about 428.0029969657.

The spelling of 78404399 in words is "seventy-eight million, four hundred four thousand, three hundred ninety-nine".