20718638 has 4 divisors (see below), whose sum is σ = 31077960. Its totient is φ = 10359318.

The previous prime is 20718637. The next prime is 20718661. The reversal of 20718638 is 83681702.

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

It is a junction number, because it is equal to n+sod(n) for n = 20718598 and 20718607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20718637) 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 as a sum of consecutive naturals, namely, 5179658 + ... + 5179661.

It is an arithmetic number, because the mean of its divisors is an integer number (7769490).

Almost surely, 2^20718638 is an apocalyptic number.

20718638 is a deficient number, since it is larger than the sum of its proper divisors (10359322).

20718638 is a wasteful number, since it uses less digits than its factorization.

20718638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10359321.

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 20718638 is about 4551.7730611268. The cubic root of 20718638 is about 274.6547203804.

The spelling of 20718638 in words is "twenty million, seven hundred eighteen thousand, six hundred thirty-eight".