216582491 has 2 divisors, whose sum is σ = 216582492. Its totient is φ = 216582490.

The previous prime is 216582449. The next prime is 216582493. The reversal of 216582491 is 194285612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 216582491 - 2¹⁸ = 216320347 is a prime.

Together with 216582493, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (216582493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108291245 + 108291246.

It is an arithmetic number, because the mean of its divisors is an integer number (108291246).

Almost surely, 2^216582491 is an apocalyptic number.

216582491 is a deficient number, since it is larger than the sum of its proper divisors (1).

216582491 is an equidigital number, since it uses as much as digits as its factorization.

216582491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34560, while the sum is 38.

The square root of 216582491 is about 14716.7418608876. The cubic root of 216582491 is about 600.5388594245.

It can be divided in two parts, 21658 and 2491, that multiplied together give a triangular number (53950078 = T₁₀₃₈₇).

The spelling of 216582491 in words is "two hundred sixteen million, five hundred eighty-two thousand, four hundred ninety-one".