20509443 has 12 divisors (see below), whose sum is σ = 30722328. Its totient is φ = 13672800.

The previous prime is 20509421. The next prime is 20509453. The reversal of 20509443 is 34490502.

It is not a de Polignac number, because 20509443 - 2⁸ = 20509187 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (20509453) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41958 + ... + 42443.

It is an arithmetic number, because the mean of its divisors is an integer number (2560194).

Almost surely, 2^20509443 is an apocalyptic number.

20509443 is a deficient number, since it is larger than the sum of its proper divisors (10212885).

20509443 is an frugal number, since it uses more digits than its factorization.

20509443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84416 (or 84404 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 20509443 is about 4528.7352539092. The cubic root of 20509443 is about 273.7272002028.

Adding to 20509443 its reverse (34490502), we get a palindrome (54999945).

The spelling of 20509443 in words is "twenty million, five hundred nine thousand, four hundred forty-three".