636641001 has 6 divisors (see below), whose sum is σ = 919592570. Its totient is φ = 424427328.

The previous prime is 636640997. The next prime is 636641023. The reversal of 636641001 is 100146636.

It can be written as a sum of positive squares in only one way, i.e., 603979776 + 32661225 = 24576^2 + 5715^2 .

It is not a de Polignac number, because 636641001 - 2² = 636640997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (636641051) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35368936 + ... + 35368953.

Almost surely, 2^636641001 is an apocalyptic number.

It is an amenable number.

636641001 is a deficient number, since it is larger than the sum of its proper divisors (282951569).

636641001 is a wasteful number, since it uses less digits than its factorization.

636641001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70737895 (or 70737892 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 636641001 is about 25231.7458967865. The cubic root of 636641001 is about 860.2635756912.

Adding to 636641001 its reverse (100146636), we get a palindrome (736787637).

The spelling of 636641001 in words is "six hundred thirty-six million, six hundred forty-one thousand, one".