636551797 has 6 divisors (see below), whose sum is σ = 740478678. Its totient is φ = 545615784.

The previous prime is 636551789. The next prime is 636551803. The reversal of 636551797 is 797155636.

It can be written as a sum of positive squares in only one way, i.e., 411521796 + 225030001 = 20286^2 + 15001^2 .

It is not a de Polignac number, because 636551797 - 2³ = 636551789 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49), and also a Moran number because the ratio is a prime number: 12990853 = 636551797 / (6 + 3 + 6 + 5 + 5 + 1 + 7 + 9 + 7).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 636551797.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636551717) 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, 6495378 + ... + 6495475.

It is an arithmetic number, because the mean of its divisors is an integer number (123413113).

Almost surely, 2^636551797 is an apocalyptic number.

It is an amenable number.

636551797 is a deficient number, since it is larger than the sum of its proper divisors (103926881).

636551797 is a wasteful number, since it uses less digits than its factorization.

636551797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12990867 (or 12990860 counting only the distinct ones).

The product of its digits is 1190700, while the sum is 49.

The square root of 636551797 is about 25229.9781410924. The cubic root of 636551797 is about 860.2233947329.

The spelling of 636551797 in words is "six hundred thirty-six million, five hundred fifty-one thousand, seven hundred ninety-seven".