81971910 has 24 divisors (see below), whose sum is σ = 213127200. Its totient is φ = 21859152.

The previous prime is 81971873. The next prime is 81971917. The reversal of 81971910 is 1917918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81971917) 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, 455310 + ... + 455489.

It is an arithmetic number, because the mean of its divisors is an integer number (8880300).

Almost surely, 2^81971910 is an apocalyptic number.

81971910 is an abundant number, since it is smaller than the sum of its proper divisors (131155290).

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

81971910 is a wasteful number, since it uses less digits than its factorization.

81971910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 910812 (or 910809 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 36.

The square root of 81971910 is about 9053.8339945020. The cubic root of 81971910 is about 434.3985345839.

The spelling of 81971910 in words is "eighty-one million, nine hundred seventy-one thousand, nine hundred ten".