636551 has 4 divisors (see below), whose sum is σ = 647400. Its totient is φ = 625704.

The previous prime is 636547. The next prime is 636553. The reversal of 636551 is 155636.

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

It is a cyclic number.

It is not a de Polignac number, because 636551 - 2² = 636547 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 636551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636553) 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, 5336 + ... + 5453.

It is an arithmetic number, because the mean of its divisors is an integer number (161850).

2⁶³⁶⁵⁵¹ is an apocalyptic number.

636551 is a deficient number, since it is larger than the sum of its proper divisors (10849).

636551 is a wasteful number, since it uses less digits than its factorization.

636551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10848.

The product of its digits is 2700, while the sum is 26.

The square root of 636551 is about 797.8414629486. The cubic root of 636551 is about 86.0223035716.

The spelling of 636551 in words is "six hundred thirty-six thousand, five hundred fifty-one".