636989 has 4 divisors (see below), whose sum is σ = 638880. Its totient is φ = 635100.

The previous prime is 636983. The next prime is 636997. The reversal of 636989 is 989636.

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 636989 - 2¹⁶ = 571453 is a prime.

It is a super-2 number, since 2×636989² = 811509972242, which contains 22 as substring.

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

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 636989.

It is not an unprimeable number, because it can be changed into a prime (636983) 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, 287 + ... + 1164.

It is an arithmetic number, because the mean of its divisors is an integer number (159720).

2⁶³⁶⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

636989 is a deficient number, since it is larger than the sum of its proper divisors (1891).

636989 is a wasteful number, since it uses less digits than its factorization.

636989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1890.

The product of its digits is 69984, while the sum is 41.

The square root of 636989 is about 798.1159063695. The cubic root of 636989 is about 86.0420292131.

The spelling of 636989 in words is "six hundred thirty-six thousand, nine hundred eighty-nine".