20928643 has 8 divisors (see below), whose sum is σ = 22429728. Its totient is φ = 19476864.

The previous prime is 20928637. The next prime is 20928647. The reversal of 20928643 is 34682902.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20928643 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20928599 and 20928608.

It is not an unprimeable number, because it can be changed into a prime (20928647) 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 7 ways as a sum of consecutive naturals, for example, 11446 + ... + 13147.

It is an arithmetic number, because the mean of its divisors is an integer number (2803716).

Almost surely, 2^20928643 is an apocalyptic number.

20928643 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

20928643 is a deficient number, since it is larger than the sum of its proper divisors (1501085).

20928643 is a wasteful number, since it uses less digits than its factorization.

20928643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24653.

The product of its (nonzero) digits is 20736, while the sum is 34.

The square root of 20928643 is about 4574.7833828499. The cubic root of 20928643 is about 275.5795732609.

The spelling of 20928643 in words is "twenty million, nine hundred twenty-eight thousand, six hundred forty-three".