• 636 can be written using four 4's:

636 has 12 divisors (see below), whose sum is σ = 1512. Its totient is φ = 208.

The previous prime is 631. The next prime is 641.

636 = 4^{2} + 5^{2} + ... + 12^{2}.

636 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (631) and next prime (641).

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (15) coincides with the sum of the digits of its prime factors.

It is a nude number because it is divisible by every one of its digits.

It is an alternating number because its digits alternate between even and odd.

636 is an undulating number in base 10.

It is a plaindrome in base 7, base 13, base 14 and base 16.

It is a nialpdrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (631) 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, 15 + ... + 38.

It is an arithmetic number, because the mean of its divisors is an integer number (126).

It is an amenable number.

636 is an abundant number, since it is smaller than the sum of its proper divisors (876).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (756).

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

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

The sum of its prime factors is 60 (or 58 counting only the distinct ones).

The product of its digits is 108, while the sum is 15.

The square root of 636 is about 25.2190404258. The cubic root of 636 is about 8.5997476039.

Subtracting from 636 its product of digits (108), we obtain a triangular number (528 = T_{32}).

It can be divided in two parts, 63 and 6, that multiplied together give a triangular number (378 = T_{27}).

The spelling of 636 in words is "six hundred thirty-six", and thus it is an aban number and an oban number.

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