216332981 has 2 divisors, whose sum is σ = 216332982. Its totient is φ = 216332980.

The previous prime is 216332971. The next prime is 216332983. The reversal of 216332981 is 189233612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 135512881 + 80820100 = 11641^2 + 8990^2 .

It is a cyclic number.

It is not a de Polignac number, because 216332981 - 2¹⁰ = 216331957 is a prime.

It is a super-2 number, since 2×216332981² = 93599917336692722, which contains 22 as substring.

Together with 216332983, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_11931776 and since 216332981 and 11931776 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216332983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108166490 + 108166491.

It is an arithmetic number, because the mean of its divisors is an integer number (108166491).

Almost surely, 2^216332981 is an apocalyptic number.

It is an amenable number.

216332981 is a deficient number, since it is larger than the sum of its proper divisors (1).

216332981 is an equidigital number, since it uses as much as digits as its factorization.

216332981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 35.

The square root of 216332981 is about 14708.2623378834. The cubic root of 216332981 is about 600.3081574453.

The spelling of 216332981 in words is "two hundred sixteen million, three hundred thirty-two thousand, nine hundred eighty-one".