8216781 has 8 divisors (see below), whose sum is σ = 10988160. Its totient is φ = 5461632.

The previous prime is 8216777. The next prime is 8216783. The reversal of 8216781 is 1876128.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 8216781 - 2² = 8216777 is a prime.

It is a super-2 number, since 2×8216781² = 135030980003922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8216783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2821 + ... + 4938.

It is an arithmetic number, because the mean of its divisors is an integer number (1373520).

Almost surely, 2^8216781 is an apocalyptic number.

It is an amenable number.

8216781 is a deficient number, since it is larger than the sum of its proper divisors (2771379).

8216781 is a wasteful number, since it uses less digits than its factorization.

8216781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8115.

The product of its digits is 5376, while the sum is 33.

The square root of 8216781 is about 2866.4928048052. The cubic root of 8216781 is about 201.7904322657.

The spelling of 8216781 in words is "eight million, two hundred sixteen thousand, seven hundred eighty-one".