216991583 has 2 divisors, whose sum is σ = 216991584. Its totient is φ = 216991582.

The previous prime is 216991573. The next prime is 216991633. The reversal of 216991583 is 385199612.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 216991583 - 2¹⁰ = 216990559 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216991513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108495791 + 108495792.

It is an arithmetic number, because the mean of its divisors is an integer number (108495792).

Almost surely, 2^216991583 is an apocalyptic number.

216991583 is a deficient number, since it is larger than the sum of its proper divisors (1).

216991583 is an equidigital number, since it uses as much as digits as its factorization.

216991583 is an evil number, because the sum of its binary digits is even.

The product of its digits is 116640, while the sum is 44.

The square root of 216991583 is about 14730.6341682902. The cubic root of 216991583 is about 600.9167310344.

The spelling of 216991583 in words is "two hundred sixteen million, nine hundred ninety-one thousand, five hundred eighty-three".