20643328 has 40 divisors (see below), whose sum is σ = 43064208. Its totient is φ = 9867264.

The previous prime is 20643323. The next prime is 20643347. The reversal of 20643328 is 82334602.

It is a super-2 number, since 2×20643328² = 852293981831168, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20643296 and 20643305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20643323) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10900 + ... + 12652.

Almost surely, 2^20643328 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20643328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21532104).

20643328 is an abundant number, since it is smaller than the sum of its proper divisors (22420880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20643328 is an equidigital number, since it uses as much as digits as its factorization.

20643328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1794 (or 1778 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 28.

The square root of 20643328 is about 4543.4929294542. The cubic root of 20643328 is about 274.3215363267.

It can be divided in two parts, 206 and 43328, that added together give a palindrome (43534).

The spelling of 20643328 in words is "twenty million, six hundred forty-three thousand, three hundred twenty-eight".