636641 has 4 divisors (see below), whose sum is σ = 638484. Its totient is φ = 634800.

The previous prime is 636631. The next prime is 636653. The reversal of 636641 is 146636.

636641 is nontrivially palindromic in base 5.

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 246016 + 390625 = 496^2 + 625^2 .

It is a cyclic number.

It is not a de Polignac number, because 636641 - 2¹⁰ = 635617 is a prime.

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 636641.

It is not an unprimeable number, because it can be changed into a prime (636631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 230 + ... + 1151.

It is an arithmetic number, because the mean of its divisors is an integer number (159621).

2⁶³⁶⁶⁴¹ is an apocalyptic number.

636641 is the 461-st octagonal number.

It is an amenable number.

636641 is a deficient number, since it is larger than the sum of its proper divisors (1843).

636641 is a wasteful number, since it uses less digits than its factorization.

636641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1842.

The product of its digits is 2592, while the sum is 26.

The square root of 636641 is about 797.8978631379. The cubic root of 636641 is about 86.0263575241.

The spelling of 636641 in words is "six hundred thirty-six thousand, six hundred forty-one".