393787993 has 4 divisors (see below), whose sum is σ = 395320500. Its totient is φ = 392255488.

The previous prime is 393787969. The next prime is 393787997. The reversal of 393787993 is 399787393.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 399787393 = 103 ⋅3881431.

It can be written as a sum of positive squares in 2 ways, for example, as 326597184 + 67190809 = 18072^2 + 8197^2 .

It is a cyclic number.

It is not a de Polignac number, because 393787993 - 2²⁵ = 360233561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (393787997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 765868 + ... + 766381.

It is an arithmetic number, because the mean of its divisors is an integer number (98830125).

Almost surely, 2^393787993 is an apocalyptic number.

It is an amenable number.

393787993 is a deficient number, since it is larger than the sum of its proper divisors (1532507).

393787993 is a wasteful number, since it uses less digits than its factorization.

393787993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1532506.

The product of its digits is 7715736, while the sum is 58.

The square root of 393787993 is about 19844.0921435071. The cubic root of 393787993 is about 732.9721777900.

The spelling of 393787993 in words is "three hundred ninety-three million, seven hundred eighty-seven thousand, nine hundred ninety-three".