20638 has 8 divisors (see below), whose sum is σ = 32832. Its totient is φ = 9696.

The previous prime is 20627. The next prime is 20639. The reversal of 20638 is 83602.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20639) by changing a digit.

20638 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 270 + ... + 337.

It is an arithmetic number, because the mean of its divisors is an integer number (4104).

2²⁰⁶³⁸ is an apocalyptic number.

20638 is a deficient number, since it is larger than the sum of its proper divisors (12194).

20638 is a wasteful number, since it uses less digits than its factorization.

20638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 626.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 20638 is about 143.6593192243. The cubic root of 20638 is about 27.4297933690.

The spelling of 20638 in words is "twenty thousand, six hundred thirty-eight".