8216865981 has 24 divisors (see below), whose sum is σ = 12143389440. Its totient is φ = 5352372000.

The previous prime is 8216865973. The next prime is 8216865991. The reversal of 8216865981 is 1895686128.

It is a happy number.

It is not a de Polignac number, because 8216865981 - 2³ = 8216865973 is a prime.

It is a super-2 number, since 2×8216865981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8216865931) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33340 + ... + 132458.

It is an arithmetic number, because the mean of its divisors is an integer number (505974560).

Almost surely, 2^8216865981 is an apocalyptic number.

It is an amenable number.

8216865981 is a deficient number, since it is larger than the sum of its proper divisors (3926523459).

8216865981 is a wasteful number, since it uses less digits than its factorization.

8216865981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99337 (or 99334 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 54.

The square root of 8216865981 is about 90646.9303451584. The cubic root of 8216865981 is about 2017.9112792718.

The spelling of 8216865981 in words is "eight billion, two hundred sixteen million, eight hundred sixty-five thousand, nine hundred eighty-one".