636720399 has 32 divisors (see below), whose sum is σ = 1084554240. Its totient is φ = 361643616.

The previous prime is 636720373. The next prime is 636720401. The reversal of 636720399 is 993027636.

636720399 is a `hidden beast` number, since 636 + 7 + 2 + 0 + 3 + 9 + 9 = 666.

It is not a de Polignac number, because 636720399 - 2¹² = 636716303 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636720199) 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 31 ways as a sum of consecutive naturals, for example, 21477 + ... + 41649.

It is an arithmetic number, because the mean of its divisors is an integer number (33892320).

Almost surely, 2^636720399 is an apocalyptic number.

636720399 is a deficient number, since it is larger than the sum of its proper divisors (447833841).

636720399 is a wasteful number, since it uses less digits than its factorization.

636720399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20356 (or 20350 counting only the distinct ones).

The product of its (nonzero) digits is 367416, while the sum is 45.

The square root of 636720399 is about 25233.3192228054. The cubic root of 636720399 is about 860.2993364878.

The spelling of 636720399 in words is "six hundred thirty-six million, seven hundred twenty thousand, three hundred ninety-nine".