636491197 has 4 divisors (see below), whose sum is σ = 640763100. Its totient is φ = 632219296.

The previous prime is 636491189. The next prime is 636491269. The reversal of 636491197 is 791194636.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 46049796 + 590441401 = 6786^2 + 24299^2 .

It is a cyclic number.

It is not a de Polignac number, because 636491197 - 2³ = 636491189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636491137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2135728 + ... + 2136025.

It is an arithmetic number, because the mean of its divisors is an integer number (160190775).

Almost surely, 2^636491197 is an apocalyptic number.

It is an amenable number.

636491197 is a deficient number, since it is larger than the sum of its proper divisors (4271903).

636491197 is a wasteful number, since it uses less digits than its factorization.

636491197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4271902.

The product of its digits is 244944, while the sum is 46.

The square root of 636491197 is about 25228.7771602192. Note that the first 3 decimals coincide. The cubic root of 636491197 is about 860.1960959898.

It can be divided in two parts, 63649 and 1197, that added together give a palindrome (64846).

The spelling of 636491197 in words is "six hundred thirty-six million, four hundred ninety-one thousand, one hundred ninety-seven".