20909643 has 8 divisors (see below), whose sum is σ = 29519568. Its totient is φ = 13119744.

The previous prime is 20909621. The next prime is 20909657. The reversal of 20909643 is 34690902.

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

It is not a de Polignac number, because 20909643 - 2⁸ = 20909387 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20909743) 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, 204946 + ... + 205047.

It is an arithmetic number, because the mean of its divisors is an integer number (3689946).

Almost surely, 2^20909643 is an apocalyptic number.

20909643 is a deficient number, since it is larger than the sum of its proper divisors (8609925).

20909643 is a wasteful number, since it uses less digits than its factorization.

20909643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410013.

The product of its (nonzero) digits is 11664, while the sum is 33.

The square root of 20909643 is about 4572.7063102719. The cubic root of 20909643 is about 275.4961533406.

The spelling of 20909643 in words is "twenty million, nine hundred nine thousand, six hundred forty-three".