20728939 has 16 divisors (see below), whose sum is σ = 26737920. Its totient is φ = 15593760.

The previous prime is 20728921. The next prime is 20728949. The reversal of 20728939 is 93982702.

It is not a de Polignac number, because 20728939 - 2⁵ = 20728907 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20728919) 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 15 ways as a sum of consecutive naturals, for example, 2409 + ... + 6874.

It is an arithmetic number, because the mean of its divisors is an integer number (1671120).

Almost surely, 2^20728939 is an apocalyptic number.

20728939 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

20728939 is a deficient number, since it is larger than the sum of its proper divisors (6008981).

20728939 is a wasteful number, since it uses less digits than its factorization.

20728939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9330.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 20728939 is about 4552.9044575963. The cubic root of 20728939 is about 274.7002309254.

It can be divided in two parts, 2072 and 8939, that added together give a palindrome (11011).

The spelling of 20728939 in words is "twenty million, seven hundred twenty-eight thousand, nine hundred thirty-nine".