216298781 has 12 divisors (see below), whose sum is σ = 225434772. Its totient is φ = 207380736.

The previous prime is 216298759. The next prime is 216298813. The reversal of 216298781 is 187892612.

It can be written as a sum of positive squares in 6 ways, for example, as 7236100 + 209062681 = 2690^2 + 14459^2 .

It is not a de Polignac number, because 216298781 - 2¹⁸ = 216036637 is a prime.

It is a super-2 number, since 2×216298781² = 93570325324171922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216298721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 196625 + ... + 197721.

It is an arithmetic number, because the mean of its divisors is an integer number (18786231).

Almost surely, 2^216298781 is an apocalyptic number.

It is an amenable number.

216298781 is a deficient number, since it is larger than the sum of its proper divisors (9135991).

216298781 is an equidigital number, since it uses as much as digits as its factorization.

216298781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1280 (or 1207 counting only the distinct ones).

The product of its digits is 96768, while the sum is 44.

The square root of 216298781 is about 14707.0996800865. The cubic root of 216298781 is about 600.2765216142.

The spelling of 216298781 in words is "two hundred sixteen million, two hundred ninety-eight thousand, seven hundred eighty-one".