20505571 has 2 divisors, whose sum is σ = 20505572. Its totient is φ = 20505570.

The previous prime is 20505497. The next prime is 20505593. The reversal of 20505571 is 17550502.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20505571 - 2¹¹ = 20503523 is a prime.

It is not a weakly prime, because it can be changed into another prime (20502571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10252785 + 10252786.

It is an arithmetic number, because the mean of its divisors is an integer number (10252786).

Almost surely, 2^20505571 is an apocalyptic number.

20505571 is a deficient number, since it is larger than the sum of its proper divisors (1).

20505571 is an equidigital number, since it uses as much as digits as its factorization.

20505571 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1750, while the sum is 25.

The square root of 20505571 is about 4528.3077413091. The cubic root of 20505571 is about 273.7099733670.

The spelling of 20505571 in words is "twenty million, five hundred five thousand, five hundred seventy-one".