217842538109 has 4 divisors (see below), whose sum is σ = 248962900704. Its totient is φ = 186722175516.

The previous prime is 217842538073. The next prime is 217842538141. The reversal of 217842538109 is 901835248712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 217842538109 - 2⁸ = 217842537853 is a prime.

It is a super-2 number, since 2×217842538109² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217842538009) 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, 15560181287 + ... + 15560181300.

It is an arithmetic number, because the mean of its divisors is an integer number (62240725176).

Almost surely, 2^217842538109 is an apocalyptic number.

It is an amenable number.

217842538109 is a deficient number, since it is larger than the sum of its proper divisors (31120362595).

217842538109 is an equidigital number, since it uses as much as digits as its factorization.

217842538109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31120362594.

The product of its (nonzero) digits is 967680, while the sum is 50.

The spelling of 217842538109 in words is "two hundred seventeen billion, eight hundred forty-two million, five hundred thirty-eight thousand, one hundred nine".