999978387 has 12 divisors (see below), whose sum is σ = 1336971720. Its totient is φ = 664822912.

The previous prime is 999978367. The next prime is 999978407. The reversal of 999978387 is 783879999.

It is an interprime number because it is at equal distance from previous prime (999978367) and next prime (999978407).

It is not a de Polignac number, because 999978387 - 2¹¹ = 999976339 is a prime.

It is a Smith number, since the sum of its digits (69) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (999978367) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1075939 + ... + 1076867.

It is an arithmetic number, because the mean of its divisors is an integer number (111414310).

Almost surely, 2^999978387 is an apocalyptic number.

999978387 is a deficient number, since it is larger than the sum of its proper divisors (336993333).

999978387 is an frugal number, since it uses more digits than its factorization.

999978387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2130 (or 1531 counting only the distinct ones).

The product of its digits is 61725888, while the sum is 69.

The square root of 999978387 is about 31622.4348683020. The cubic root of 999978387 is about 999.9927956148.

The spelling of 999978387 in words is "nine hundred ninety-nine million, nine hundred seventy-eight thousand, three hundred eighty-seven".