217616081 has 4 divisors (see below), whose sum is σ = 218359092. Its totient is φ = 216873072.

The previous prime is 217616071. The next prime is 217616083. The reversal of 217616081 is 180616712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 153760000 + 63856081 = 12400^2 + 7991^2 .

It is a cyclic number.

It is not a de Polignac number, because 217616081 - 2⁶ = 217616017 is a prime.

It is a super-2 number, since 2×217616081² = 94713517419597122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217616083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 371066 + ... + 371651.

It is an arithmetic number, because the mean of its divisors is an integer number (54589773).

Almost surely, 2^217616081 is an apocalyptic number.

It is an amenable number.

217616081 is a deficient number, since it is larger than the sum of its proper divisors (743011).

217616081 is an equidigital number, since it uses as much as digits as its factorization.

217616081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 743010.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 217616081 is about 14751.8161932692. The cubic root of 217616081 is about 601.4926548528.

The spelling of 217616081 in words is "two hundred seventeen million, six hundred sixteen thousand, eighty-one".