217640805471553 has 2 divisors, whose sum is σ = 217640805471554. Its totient is φ = 217640805471552.

The previous prime is 217640805471503. The next prime is 217640805471619. The reversal of 217640805471553 is 355174508046712.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 158091695196304 + 59549110275249 = 12573452^2 + 7716807^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217640805471553 is a prime.

It is not a weakly prime, because it can be changed into another prime (217640805471503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108820402735776 + 108820402735777.

It is an arithmetic number, because the mean of its divisors is an integer number (108820402735777).

Almost surely, 2^{217640805471553} is an apocalyptic number.

It is an amenable number.

217640805471553 is a deficient number, since it is larger than the sum of its proper divisors (1).

217640805471553 is an equidigital number, since it uses as much as digits as its factorization.

217640805471553 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28224000, while the sum is 58.

The spelling of 217640805471553 in words is "two hundred seventeen trillion, six hundred forty billion, eight hundred five million, four hundred seventy-one thousand, five hundred fifty-three".