20557521571 has 8 divisors (see below), whose sum is σ = 21392141760. Its totient is φ = 19739107752.

The previous prime is 20557521557. The next prime is 20557521581. The reversal of 20557521571 is 17512575502.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20557521571 - 2²³ = 20549132963 is a prime.

It is a super-2 number, since 2×20557521571² (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 (20557521581) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4049005 + ... + 4054078.

It is an arithmetic number, because the mean of its divisors is an integer number (2674017720).

Almost surely, 2^20557521571 is an apocalyptic number.

20557521571 is a deficient number, since it is larger than the sum of its proper divisors (834620189).

20557521571 is an equidigital number, since it uses as much as digits as its factorization.

20557521571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8103185.

The product of its (nonzero) digits is 122500, while the sum is 40.

The spelling of 20557521571 in words is "twenty billion, five hundred fifty-seven million, five hundred twenty-one thousand, five hundred seventy-one".