20728739 has 16 divisors (see below), whose sum is σ = 22450176. Its totient is φ = 19099200.

The previous prime is 20728733. The next prime is 20728759. The reversal of 20728739 is 93782702.

It is a cyclic number.

It is not a de Polignac number, because 20728739 - 2⁸ = 20728483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20728733) 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, 59564 + ... + 59910.

It is an arithmetic number, because the mean of its divisors is an integer number (1403136).

Almost surely, 2^20728739 is an apocalyptic number.

20728739 is a deficient number, since it is larger than the sum of its proper divisors (1721437).

20728739 is a wasteful number, since it uses less digits than its factorization.

20728739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 466.

The product of its (nonzero) digits is 42336, while the sum is 38.

The square root of 20728739 is about 4552.8824935419. The cubic root of 20728739 is about 274.6993474548.

The spelling of 20728739 in words is "twenty million, seven hundred twenty-eight thousand, seven hundred thirty-nine".