645571 has 2 divisors, whose sum is σ = 645572. Its totient is φ = 645570.

The previous prime is 645529. The next prime is 645577. The reversal of 645571 is 175546.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645571 - 2⁷ = 645443 is a prime.

It is a Chen prime.

It is a nialpdrome in base 15.

It is not a weakly prime, because it can be changed into another prime (645577) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322785 + 322786.

It is an arithmetic number, because the mean of its divisors is an integer number (322786).

2⁶⁴⁵⁵⁷¹ is an apocalyptic number.

645571 is a deficient number, since it is larger than the sum of its proper divisors (1).

645571 is an equidigital number, since it uses as much as digits as its factorization.

645571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4200, while the sum is 28.

The square root of 645571 is about 803.4743306416. The cubic root of 645571 is about 86.4267146329.

The spelling of 645571 in words is "six hundred forty-five thousand, five hundred seventy-one".