861998181 has 16 divisors (see below), whose sum is σ = 1254397440. Its totient is φ = 522180720.

The previous prime is 861998173. The next prime is 861998191. The reversal of 861998181 is 181899168.

It is not a de Polignac number, because 861998181 - 2³ = 861998173 is a prime.

It is a super-2 number, since 2×861998181² = 1486081728094617522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861998101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87840 + ... + 97158.

It is an arithmetic number, because the mean of its divisors is an integer number (78399840).

Almost surely, 2^861998181 is an apocalyptic number.

It is an amenable number.

861998181 is a deficient number, since it is larger than the sum of its proper divisors (392399259).

861998181 is a wasteful number, since it uses less digits than its factorization.

861998181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12136.

The product of its digits is 248832, while the sum is 51.

The square root of 861998181 is about 29359.8055340971. The cubic root of 861998181 is about 951.7044860649.

The spelling of 861998181 in words is "eight hundred sixty-one million, nine hundred ninety-eight thousand, one hundred eighty-one".