217240823 has 2 divisors, whose sum is σ = 217240824. Its totient is φ = 217240822.

The previous prime is 217240787. The next prime is 217240843. The reversal of 217240823 is 328042712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 217240823 - 2¹⁸ = 216978679 is a prime.

It is a super-3 number, since 3×217240823³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217240843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108620411 + 108620412.

It is an arithmetic number, because the mean of its divisors is an integer number (108620412).

Almost surely, 2^217240823 is an apocalyptic number.

217240823 is a deficient number, since it is larger than the sum of its proper divisors (1).

217240823 is an equidigital number, since it uses as much as digits as its factorization.

217240823 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5376, while the sum is 29.

The square root of 217240823 is about 14739.0916612931. The cubic root of 217240823 is about 601.1467171885.

The spelling of 217240823 in words is "two hundred seventeen million, two hundred forty thousand, eight hundred twenty-three".