81861010 has 64 divisors (see below), whose sum is σ = 188262144. Its totient is φ = 24883200.

The previous prime is 81860971. The next prime is 81861011. The reversal of 81861010 is 1016818.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81861011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 30274 + ... + 32866.

It is an arithmetic number, because the mean of its divisors is an integer number (2941596).

Almost surely, 2^81861010 is an apocalyptic number.

81861010 is an abundant number, since it is smaller than the sum of its proper divisors (106401134).

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

81861010 is a wasteful number, since it uses less digits than its factorization.

81861010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2659.

The product of its (nonzero) digits is 384, while the sum is 25.

The square root of 81861010 is about 9047.7074444303. The cubic root of 81861010 is about 434.2025465555.

Adding to 81861010 its reverse (1016818), we get a palindrome (82877828).

The spelling of 81861010 in words is "eighty-one million, eight hundred sixty-one thousand, ten".