81866536 has 32 divisors (see below), whose sum is σ = 163929600. Its totient is φ = 38243520.

The previous prime is 81866531. The next prime is 81866537. The reversal of 81866536 is 63566818.

It is a junction number, because it is equal to n+sod(n) for n = 81866492 and 81866501.

It is not an unprimeable number, because it can be changed into a prime (81866531) 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, 1501 + ... + 12883.

It is an arithmetic number, because the mean of its divisors is an integer number (5122800).

Almost surely, 2^81866536 is an apocalyptic number.

It is an amenable number.

81866536 is an abundant number, since it is smaller than the sum of its proper divisors (82063064).

81866536 is a wasteful number, since it uses less digits than its factorization.

81866536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11449 (or 11445 counting only the distinct ones).

The product of its digits is 207360, while the sum is 43.

The square root of 81866536 is about 9048.0128205037. The cubic root of 81866536 is about 434.2123165680.

The spelling of 81866536 in words is "eighty-one million, eight hundred sixty-six thousand, five hundred thirty-six".