86816781 has 6 divisors (see below), whose sum is σ = 125402030. Its totient is φ = 57877848.

The previous prime is 86816767. The next prime is 86816827. The reversal of 86816781 is 18761868.

It can be written as a sum of positive squares in only one way, i.e., 85266756 + 1550025 = 9234^2 + 1245^2 .

It is not a de Polignac number, because 86816781 - 2²¹ = 84719629 is a prime.

It is a super-2 number, since 2×86816781² = 15074306926403922, which 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 (86816711) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4823146 + ... + 4823163.

Almost surely, 2^86816781 is an apocalyptic number.

It is an amenable number.

86816781 is a deficient number, since it is larger than the sum of its proper divisors (38585249).

86816781 is a wasteful number, since it uses less digits than its factorization.

86816781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9646315 (or 9646312 counting only the distinct ones).

The product of its digits is 129024, while the sum is 45.

The square root of 86816781 is about 9317.5523073391. The cubic root of 86816781 is about 442.7934891070.

The spelling of 86816781 in words is "eighty-six million, eight hundred sixteen thousand, seven hundred eighty-one".