636404405 has 24 divisors (see below), whose sum is σ = 956709432. Its totient is φ = 402820992.

The previous prime is 636404387. The next prime is 636404459. The reversal of 636404405 is 504404636.

It can be written as a sum of positive squares in 4 ways, for example, as 154206724 + 482197681 = 12418^2 + 21959^2 .

It is not a de Polignac number, because 636404405 - 2⁶ = 636404341 is a prime.

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 96722 + ... + 103091.

It is an arithmetic number, because the mean of its divisors is an integer number (39862893).

Almost surely, 2^636404405 is an apocalyptic number.

636404405 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

636404405 is a deficient number, since it is larger than the sum of its proper divisors (320305027).

636404405 is a wasteful number, since it uses less digits than its factorization.

636404405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199845 (or 199838 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 32.

The square root of 636404405 is about 25227.0570023536. The cubic root of 636404405 is about 860.1569954054.

The spelling of 636404405 in words is "six hundred thirty-six million, four hundred four thousand, four hundred five".