81817901 has 8 divisors (see below), whose sum is σ = 89995008. Its totient is φ = 74378700.

The previous prime is 81817873. The next prime is 81817913. The reversal of 81817901 is 10971818.

It is a de Polignac number, because none of the positive numbers 2^k-81817901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81817301) 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, 29405 + ... + 32066.

It is an arithmetic number, because the mean of its divisors is an integer number (11249376).

Almost surely, 2^81817901 is an apocalyptic number.

It is an amenable number.

81817901 is a deficient number, since it is larger than the sum of its proper divisors (8177107).

81817901 is an equidigital number, since it uses as much as digits as its factorization.

81817901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61504 (or 61482 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 35.

The square root of 81817901 is about 9045.3248145105. The cubic root of 81817901 is about 434.1263143978.

The spelling of 81817901 in words is "eighty-one million, eight hundred seventeen thousand, nine hundred one".