636491 has 4 divisors (see below), whose sum is σ = 638232. Its totient is φ = 634752.

The previous prime is 636473. The next prime is 636499. The reversal of 636491 is 194636.

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 636491 - 2¹⁸ = 374347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (636499) 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, 86 + ... + 1131.

It is an arithmetic number, because the mean of its divisors is an integer number (159558).

2⁶³⁶⁴⁹¹ is an apocalyptic number.

636491 is a deficient number, since it is larger than the sum of its proper divisors (1741).

636491 is a wasteful number, since it uses less digits than its factorization.

636491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1740.

The product of its digits is 3888, while the sum is 29.

The square root of 636491 is about 797.8038606074. The cubic root of 636491 is about 86.0196007243.

The spelling of 636491 in words is "six hundred thirty-six thousand, four hundred ninety-one".