20528643 has 4 divisors (see below), whose sum is σ = 27371528. Its totient is φ = 13685760.

The previous prime is 20528623. The next prime is 20528647. The reversal of 20528643 is 34682502.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 20528643 - 2¹⁷ = 20397571 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20528643.

It is not an unprimeable number, because it can be changed into a prime (20528647) 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, 3421438 + ... + 3421443.

It is an arithmetic number, because the mean of its divisors is an integer number (6842882).

Almost surely, 2^20528643 is an apocalyptic number.

20528643 is a deficient number, since it is larger than the sum of its proper divisors (6842885).

20528643 is an equidigital number, since it uses as much as digits as its factorization.

20528643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6842884.

The product of its (nonzero) digits is 11520, while the sum is 30.

The square root of 20528643 is about 4530.8545551584. The cubic root of 20528643 is about 273.8125905129.

The spelling of 20528643 in words is "twenty million, five hundred twenty-eight thousand, six hundred forty-three".