64639 has 4 divisors (see below), whose sum is σ = 66424. Its totient is φ = 62856.

The previous prime is 64633. The next prime is 64661. The reversal of 64639 is 93646.

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 64639 - 2¹¹ = 62591 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 837 + ... + 910.

It is an arithmetic number, because the mean of its divisors is an integer number (16606).

2⁶⁴⁶³⁹ is an apocalyptic number.

64639 is a deficient number, since it is larger than the sum of its proper divisors (1785).

64639 is a wasteful number, since it uses less digits than its factorization.

64639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1784.

The product of its digits is 3888, while the sum is 28.

The square root of 64639 is about 254.2420106906. The cubic root of 64639 is about 40.1326843847.

It can be divided in two parts, 64 and 639, that added together give a triangular number (703 = T₃₇).

The spelling of 64639 in words is "sixty-four thousand, six hundred thirty-nine".