81861876 has 36 divisors (see below), whose sum is σ = 215927712. Its totient is φ = 26100624.

The previous prime is 81861869. The next prime is 81861877. The reversal of 81861876 is 67816818.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81861877) 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 11 ways as a sum of consecutive naturals, for example, 48606 + ... + 50261.

It is an arithmetic number, because the mean of its divisors is an integer number (5997992).

Almost surely, 2^81861876 is an apocalyptic number.

It is an amenable number.

81861876 is an abundant number, since it is smaller than the sum of its proper divisors (134065836).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81861876 is a wasteful number, since it uses less digits than its factorization.

81861876 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98900 (or 98895 counting only the distinct ones).

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

The square root of 81861876 is about 9047.7553017309. The cubic root of 81861876 is about 434.2040776795.

The spelling of 81861876 in words is "eighty-one million, eight hundred sixty-one thousand, eight hundred seventy-six".