81857010 has 16 divisors (see below), whose sum is σ = 196456896. Its totient is φ = 21828528.

The previous prime is 81856991. The next prime is 81857063. The reversal of 81857010 is 1075818.

It is a super-2 number, since 2×81857010² = 13401140172280200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 2728567 = 81857010 / (8 + 1 + 8 + 5 + 7 + 0 + 1 + 0).

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1364254 + ... + 1364313.

It is an arithmetic number, because the mean of its divisors is an integer number (12278556).

Almost surely, 2^81857010 is an apocalyptic number.

81857010 is an abundant number, since it is smaller than the sum of its proper divisors (114599886).

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

81857010 is a wasteful number, since it uses less digits than its factorization.

81857010 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2728577.

The product of its (nonzero) digits is 2240, while the sum is 30.

The square root of 81857010 is about 9047.4863912581. The cubic root of 81857010 is about 434.1954742489.

The spelling of 81857010 in words is "eighty-one million, eight hundred fifty-seven thousand, ten".