20557509571 has 4 divisors (see below), whose sum is σ = 20557826032. Its totient is φ = 20557193112.

The previous prime is 20557509547. The next prime is 20557509631. The reversal of 20557509571 is 17590575502.

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

It is a cyclic number.

It is not a de Polignac number, because 20557509571 - 2¹⁹ = 20556985283 is a prime.

It is a super-2 number, since 2×20557509571² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20557509541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21276 + ... + 203881.

It is an arithmetic number, because the mean of its divisors is an integer number (5139456508).

Almost surely, 2^20557509571 is an apocalyptic number.

20557509571 is a deficient number, since it is larger than the sum of its proper divisors (316461).

20557509571 is an equidigital number, since it uses as much as digits as its factorization.

20557509571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316460.

The product of its (nonzero) digits is 551250, while the sum is 46.

The spelling of 20557509571 in words is "twenty billion, five hundred fifty-seven million, five hundred nine thousand, five hundred seventy-one".