81857801 has 8 divisors (see below), whose sum is σ = 84845640. Its totient is φ = 78910848.

The previous prime is 81857779. The next prime is 81857803. The reversal of 81857801 is 10875818.

It can be written as a sum of positive squares in 4 ways, for example, as 34798201 + 47059600 = 5899^2 + 6860^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81857801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81857803) 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, 6116 + ... + 14181.

It is an arithmetic number, because the mean of its divisors is an integer number (10605705).

Almost surely, 2^81857801 is an apocalyptic number.

It is an amenable number.

81857801 is a deficient number, since it is larger than the sum of its proper divisors (2987839).

81857801 is a wasteful number, since it uses less digits than its factorization.

81857801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20443.

The product of its (nonzero) digits is 17920, while the sum is 38.

The square root of 81857801 is about 9047.5301049513. The cubic root of 81857801 is about 434.1968728158.

The spelling of 81857801 in words is "eighty-one million, eight hundred fifty-seven thousand, eight hundred one".