20728643 has 8 divisors (see below), whose sum is σ = 22386000. Its totient is φ = 19080288.

The previous prime is 20728637. The next prime is 20728691. The reversal of 20728643 is 34682702.

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

It is a cyclic number.

It is not a de Polignac number, because 20728643 - 2⁶ = 20728579 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20728633) 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, 3008 + ... + 7106.

It is an arithmetic number, because the mean of its divisors is an integer number (2798250).

Almost surely, 2^20728643 is an apocalyptic number.

20728643 is a deficient number, since it is larger than the sum of its proper divisors (1657357).

20728643 is a wasteful number, since it uses less digits than its factorization.

20728643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4501.

The product of its (nonzero) digits is 16128, while the sum is 32.

The square root of 20728643 is about 4552.8719507581. The cubic root of 20728643 is about 274.6989233869.

The spelling of 20728643 in words is "twenty million, seven hundred twenty-eight thousand, six hundred forty-three".