20748639 has 8 divisors (see below), whose sum is σ = 28015360. Its totient is φ = 13657176.

The previous prime is 20748617. The next prime is 20748677. The reversal of 20748639 is 93684702.

20748639 = 281² + 282² + ... + 438².

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

It is not a de Polignac number, because 20748639 - 2⁸ = 20748383 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20748597 and 20748606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20748839) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43537 + ... + 44010.

It is an arithmetic number, because the mean of its divisors is an integer number (3501920).

Almost surely, 2^20748639 is an apocalyptic number.

20748639 is a deficient number, since it is larger than the sum of its proper divisors (7266721).

20748639 is an equidigital number, since it uses as much as digits as its factorization.

20748639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87629.

The product of its (nonzero) digits is 72576, while the sum is 39.

The square root of 20748639 is about 4555.0673979646. The cubic root of 20748639 is about 274.7872249442.

The spelling of 20748639 in words is "twenty million, seven hundred forty-eight thousand, six hundred thirty-nine".