9866156781 has 16 divisors (see below), whose sum is σ = 14174233920. Its totient is φ = 6068290560.

The previous prime is 9866156743. The next prime is 9866156789. The reversal of 9866156781 is 1876516689.

It is not a de Polignac number, because 9866156781 - 2⁶ = 9866156717 is a prime.

It is a super-2 number, since 2×9866156781² (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 (9866156789) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9805 + ... + 140813.

It is an arithmetic number, because the mean of its divisors is an integer number (885889620).

Almost surely, 2^9866156781 is an apocalyptic number.

It is an amenable number.

9866156781 is a deficient number, since it is larger than the sum of its proper divisors (4308077139).

9866156781 is a wasteful number, since it uses less digits than its factorization.

9866156781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132956.

The product of its digits is 4354560, while the sum is 57.

The square root of 9866156781 is about 99328.5295421210. The cubic root of 9866156781 is about 2144.7796029821.

The spelling of 9866156781 in words is "nine billion, eight hundred sixty-six million, one hundred fifty-six thousand, seven hundred eighty-one".