999978407 has 2 divisors, whose sum is σ = 999978408. Its totient is φ = 999978406.

The previous prime is 999978367. The next prime is 999978461. The reversal of 999978407 is 704879999.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 999978407 - 2¹⁶ = 999912871 is a prime.

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 999978407.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999978467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499989203 + 499989204.

It is an arithmetic number, because the mean of its divisors is an integer number (499989204).

Almost surely, 2^999978407 is an apocalyptic number.

999978407 is a deficient number, since it is larger than the sum of its proper divisors (1).

999978407 is an equidigital number, since it uses as much as digits as its factorization.

999978407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10287648, while the sum is 62.

The square root of 999978407 is about 31622.4351845331. The cubic root of 999978407 is about 999.9928022815.

The spelling of 999978407 in words is "nine hundred ninety-nine million, nine hundred seventy-eight thousand, four hundred seven".