20155571 has 2 divisors, whose sum is σ = 20155572. Its totient is φ = 20155570.

The previous prime is 20155547. The next prime is 20155589. The reversal of 20155571 is 17555102.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20155571 - 2¹⁸ = 19893427 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20155571.

It is not a weakly prime, because it can be changed into another prime (20155501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10077785 + 10077786.

It is an arithmetic number, because the mean of its divisors is an integer number (10077786).

Almost surely, 2^20155571 is an apocalyptic number.

20155571 is a deficient number, since it is larger than the sum of its proper divisors (1).

20155571 is an equidigital number, since it uses as much as digits as its factorization.

20155571 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1750, while the sum is 26.

The square root of 20155571 is about 4489.4956286870. The cubic root of 20155571 is about 272.1437524086.

The spelling of 20155571 in words is "twenty million, one hundred fifty-five thousand, five hundred seventy-one".