216243091 has 2 divisors, whose sum is σ = 216243092. Its totient is φ = 216243090.

The previous prime is 216243089. The next prime is 216243149. The reversal of 216243091 is 190342612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 216243091 - 2¹ = 216243089 is a prime.

It is a super-2 number, since 2×216243091² = 93522148810468562, which contains 22 as substring.

Together with 216243089, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (216243031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108121545 + 108121546.

It is an arithmetic number, because the mean of its divisors is an integer number (108121546).

Almost surely, 2^216243091 is an apocalyptic number.

216243091 is a deficient number, since it is larger than the sum of its proper divisors (1).

216243091 is an equidigital number, since it uses as much as digits as its factorization.

216243091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 216243091 is about 14705.2062549289. The cubic root of 216243091 is about 600.2249998738.

The spelling of 216243091 in words is "two hundred sixteen million, two hundred forty-three thousand, ninety-one".