81866260 has 36 divisors (see below), whose sum is σ = 199989972. Its totient is φ = 28068096.

The previous prime is 81866243. The next prime is 81866263. The reversal of 81866260 is 6266818.

It can be written as a sum of positive squares in 2 ways, for example, as 64577296 + 17288964 = 8036^2 + 4158^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81866263) 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 11 ways as a sum of consecutive naturals, for example, 40789 + ... + 42748.

It is an arithmetic number, because the mean of its divisors is an integer number (5555277).

Almost surely, 2^81866260 is an apocalyptic number.

It is an amenable number.

81866260 is an abundant number, since it is smaller than the sum of its proper divisors (118123712).

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

81866260 is a wasteful number, since it uses less digits than its factorization.

81866260 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83560 (or 83551 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 37.

The square root of 81866260 is about 9047.9975685231. The cubic root of 81866260 is about 434.2118286082.

The spelling of 81866260 in words is "eighty-one million, eight hundred sixty-six thousand, two hundred sixty".