8217981 has 12 divisors (see below), whose sum is σ = 12065820. Its totient is φ = 5388480.

The previous prime is 8217973. The next prime is 8217983. The reversal of 8217981 is 1897128.

It can be written as a sum of positive squares in 2 ways, for example, as 95481 + 8122500 = 309^2 + 2850^2 .

It is not a de Polignac number, because 8217981 - 2³ = 8217973 is a prime.

It is a super-2 number, since 2×8217981² = 135070423432722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8217983) 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, 6936 + ... + 8033.

It is an arithmetic number, because the mean of its divisors is an integer number (1005485).

Almost surely, 2^8217981 is an apocalyptic number.

It is an amenable number.

8217981 is a deficient number, since it is larger than the sum of its proper divisors (3847839).

8217981 is a wasteful number, since it uses less digits than its factorization.

8217981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15036 (or 15033 counting only the distinct ones).

The product of its digits is 8064, while the sum is 36.

The square root of 8217981 is about 2866.7021121840. The cubic root of 8217981 is about 201.8002551202.

The spelling of 8217981 in words is "eight million, two hundred seventeen thousand, nine hundred eighty-one".