217657397 has 4 divisors (see below), whose sum is σ = 222966156. Its totient is φ = 212348640.

The previous prime is 217657351. The next prime is 217657439. The reversal of 217657397 is 793756712.

217657397 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 97732996 + 119924401 = 9886^2 + 10951^2 .

It is a cyclic number.

It is not a de Polignac number, because 217657397 - 2¹⁴ = 217641013 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 (217657327) 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, 2654318 + ... + 2654399.

It is an arithmetic number, because the mean of its divisors is an integer number (55741539).

Almost surely, 2^217657397 is an apocalyptic number.

It is an amenable number.

217657397 is a deficient number, since it is larger than the sum of its proper divisors (5308759).

217657397 is an equidigital number, since it uses as much as digits as its factorization.

217657397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5308758.

The product of its digits is 555660, while the sum is 47.

The square root of 217657397 is about 14753.2164967508. The cubic root of 217657397 is about 601.5307183664.

The spelling of 217657397 in words is "two hundred seventeen million, six hundred fifty-seven thousand, three hundred ninety-seven".