8216832781 has 4 divisors (see below), whose sum is σ = 8219210364. Its totient is φ = 8214455200.

The previous prime is 8216832737. The next prime is 8216832787. The reversal of 8216832781 is 1872386128.

8216832781 = T₂₀₆ + T₂₀₇ + ... + T₃₆₆₆.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 845064900 + 7371767881 = 29070^2 + 85859^2 .

It is a cyclic number.

It is not a de Polignac number, because 8216832781 - 2¹¹ = 8216830733 is a prime.

It is a super-2 number, since 2×8216832781² (a number of 21 digits) 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 (8216832787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1183600 + ... + 1190521.

It is an arithmetic number, because the mean of its divisors is an integer number (2054802591).

Almost surely, 2^8216832781 is an apocalyptic number.

It is an amenable number.

8216832781 is a deficient number, since it is larger than the sum of its proper divisors (2377583).

8216832781 is a wasteful number, since it uses less digits than its factorization.

8216832781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2377582.

The product of its digits is 258048, while the sum is 46.

The square root of 8216832781 is about 90646.7472168748. The cubic root of 8216832781 is about 2017.9085614982.

It can be divided in two parts, 821683 and 2781, that added together give a square (824464 = 908²).

The spelling of 8216832781 in words is "eight billion, two hundred sixteen million, eight hundred thirty-two thousand, seven hundred eighty-one".