217423845 has 20 divisors (see below), whose sum is σ = 389753100. Its totient is φ = 115959168.

The previous prime is 217423837. The next prime is 217423849. The reversal of 217423845 is 548324712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 108618084 + 108805761 = 10422^2 + 10431^2 .

It is not a de Polignac number, because 217423845 - 2³ = 217423837 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217423849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 268020 + ... + 268829.

It is an arithmetic number, because the mean of its divisors is an integer number (19487655).

Almost surely, 2^217423845 is an apocalyptic number.

It is an amenable number.

217423845 is a deficient number, since it is larger than the sum of its proper divisors (172329255).

217423845 is an equidigital number, since it uses as much as digits as its factorization.

217423845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 536866 (or 536857 counting only the distinct ones).

The product of its digits is 53760, while the sum is 36.

The square root of 217423845 is about 14745.2990814022. The cubic root of 217423845 is about 601.3154887079.

The spelling of 217423845 in words is "two hundred seventeen million, four hundred twenty-three thousand, eight hundred forty-five".