861361735581 has 10 divisors (see below), whose sum is σ = 1286725555742. Its totient is φ = 574241157000.

The previous prime is 861361735573. The next prime is 861361735583. The reversal of 861361735581 is 185537163168.

It is a happy number.

861361735581 is a `hidden beast` number, since 8 + 6 + 13 + 6 + 1 + 73 + 558 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 437939532900 + 423422202681 = 661770^2 + 650709^2 .

It is not a de Polignac number, because 861361735581 - 2³ = 861361735573 is a prime.

It is a super-2 number, since 2×861361735581² (a number of 25 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 (861361735583) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 5317047670 + ... + 5317047831.

Almost surely, 2^861361735581 is an apocalyptic number.

861361735581 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

861361735581 is a deficient number, since it is larger than the sum of its proper divisors (425363820161).

861361735581 is a wasteful number, since it uses less digits than its factorization.

861361735581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10634095513 (or 10634095504 counting only the distinct ones).

The product of its digits is 3628800, while the sum is 54.

The spelling of 861361735581 in words is "eight hundred sixty-one billion, three hundred sixty-one million, seven hundred thirty-five thousand, five hundred eighty-one".