636638079 has 16 divisors (see below), whose sum is σ = 1058307840. Its totient is φ = 330720960.

The previous prime is 636638069. The next prime is 636638081. The reversal of 636638079 is 970836636.

It is a happy number.

It is not a de Polignac number, because 636638079 - 2⁷ = 636637951 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636638039) 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 in 15 ways as a sum of consecutive naturals, for example, 1377774 + ... + 1378235.

It is an arithmetic number, because the mean of its divisors is an integer number (66144240).

Almost surely, 2^636638079 is an apocalyptic number.

636638079 is a deficient number, since it is larger than the sum of its proper divisors (421669761).

636638079 is a wasteful number, since it uses less digits than its factorization.

636638079 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2756030.

The product of its (nonzero) digits is 979776, while the sum is 48.

The square root of 636638079 is about 25231.6879934736. The cubic root of 636638079 is about 860.2622595679.

The spelling of 636638079 in words is "six hundred thirty-six million, six hundred thirty-eight thousand, seventy-nine".