217090861 has 12 divisors (see below), whose sum is σ = 241588956. Its totient is φ = 193916160.

The previous prime is 217090843. The next prime is 217090883. The reversal of 217090861 is 168090712.

It is a happy number.

217090861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 21622500 + 195468361 = 4650^2 + 13981^2 .

It is not a de Polignac number, because 217090861 - 2⁵ = 217090829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217090361) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3805 + ... + 21181.

It is an arithmetic number, because the mean of its divisors is an integer number (20132413).

Almost surely, 2^217090861 is an apocalyptic number.

It is an amenable number.

217090861 is a deficient number, since it is larger than the sum of its proper divisors (24498095).

217090861 is a wasteful number, since it uses less digits than its factorization.

217090861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17452 (or 17421 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 217090861 is about 14734.0035631868. The cubic root of 217090861 is about 601.0083608794.

The spelling of 217090861 in words is "two hundred seventeen million, ninety thousand, eight hundred sixty-one".