636221 has 4 divisors (see below), whose sum is σ = 639744.
Its totient is φ = 632700.
The previous prime is 636217. The next prime is 636241. The reversal of 636221 is 122636.
Adding to 636221 its reverse (122636), we get a palindrome (758857).
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.
It is a cyclic number.
It is not a de Polignac number, because 636221 - 22 = 636217 is a prime.
It is a Duffinian number.
It is a Curzon number.
It is a junction number, because it is equal to n+sod(n) for n = 636193 and 636202.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (636211) 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, 1475 + ... + 1856.
It is an arithmetic number, because the mean of its divisors is an integer number (159936).
2636221 is an apocalyptic number.
It is an amenable number.
636221 is a deficient number, since it is larger than the sum of its proper divisors (3523).
636221 is a wasteful number, since it uses less digits than its factorization.
636221 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 3522.
The product of its digits is 432, while the sum is 20.
The square root of 636221 is about 797.6346281350.
The cubic root of 636221 is about 86.0074358092.
The spelling of 636221 in words is "six hundred thirty-six thousand, two hundred twenty-one".