20506571 has 12 divisors (see below), whose sum is σ = 21500952. Its totient is φ = 19546464.

The previous prime is 20506543. The next prime is 20506597. The reversal of 20506571 is 17560502.

It is a de Polignac number, because none of the positive numbers 2^k-20506571 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 20506571.

It is not an unprimeable number, because it can be changed into a prime (20506771) 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, 149615 + ... + 149751.

It is an arithmetic number, because the mean of its divisors is an integer number (1791746).

Almost surely, 2^20506571 is an apocalyptic number.

20506571 is a deficient number, since it is larger than the sum of its proper divisors (994381).

20506571 is an equidigital number, since it uses as much as digits as its factorization.

20506571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298 (or 239 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 26.

The square root of 20506571 is about 4528.4181564869. The cubic root of 20506571 is about 273.7144226542.

The spelling of 20506571 in words is "twenty million, five hundred six thousand, five hundred seventy-one".