81910081 has 8 divisors (see below), whose sum is σ = 89478144. Its totient is φ = 74362320.

The previous prime is 81910033. The next prime is 81910099. The reversal of 81910081 is 18001918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81910081 - 2⁷ = 81909953 is a prime.

It is a super-2 number, since 2×81910081² = 13418522738853122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81910681) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4096 + ... + 13438.

It is an arithmetic number, because the mean of its divisors is an integer number (11184768).

Almost surely, 2^81910081 is an apocalyptic number.

It is an amenable number.

81910081 is a deficient number, since it is larger than the sum of its proper divisors (7568063).

81910081 is a wasteful number, since it uses less digits than its factorization.

81910081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10151.

The product of its (nonzero) digits is 576, while the sum is 28.

The square root of 81910081 is about 9050.4188300874. The cubic root of 81910081 is about 434.2892891011.

Adding to 81910081 its reverse (18001918), we get a palindrome (99911999).

The spelling of 81910081 in words is "eighty-one million, nine hundred ten thousand, eighty-one".