216825391 has 2 divisors, whose sum is σ = 216825392. Its totient is φ = 216825390.

The previous prime is 216825331. The next prime is 216825419. The reversal of 216825391 is 193528612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 216825391 - 2²⁵ = 183270959 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 216825391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216825311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108412695 + 108412696.

It is an arithmetic number, because the mean of its divisors is an integer number (108412696).

Almost surely, 2^216825391 is an apocalyptic number.

216825391 is a deficient number, since it is larger than the sum of its proper divisors (1).

216825391 is an equidigital number, since it uses as much as digits as its factorization.

216825391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 37.

The square root of 216825391 is about 14724.9920543272. The cubic root of 216825391 is about 600.7632795215.

The spelling of 216825391 in words is "two hundred sixteen million, eight hundred twenty-five thousand, three hundred ninety-one".