217439371957 has 4 divisors (see below), whose sum is σ = 218640694636. Its totient is φ = 216238049280.

The previous prime is 217439371931. The next prime is 217439371973. The reversal of 217439371957 is 759173934712.

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 60972449476 + 156466922481 = 246926^2 + 395559^2 .

It is a cyclic number.

It is not a de Polignac number, because 217439371957 - 2¹⁹ = 217438847669 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 (217439371057) 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, 600661068 + ... + 600661429.

It is an arithmetic number, because the mean of its divisors is an integer number (54660173659).

Almost surely, 2^217439371957 is an apocalyptic number.

It is an amenable number.

217439371957 is a deficient number, since it is larger than the sum of its proper divisors (1201322679).

217439371957 is a wasteful number, since it uses less digits than its factorization.

217439371957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1201322678.

The product of its digits is 10001880, while the sum is 58.

The spelling of 217439371957 in words is "two hundred seventeen billion, four hundred thirty-nine million, three hundred seventy-one thousand, nine hundred fifty-seven".