81205886 has 8 divisors (see below), whose sum is σ = 128219880. Its totient is φ = 38465928.

The previous prime is 81205877. The next prime is 81205897. The reversal of 81205886 is 68850218.

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

It is a Harshad number since it is a multiple of its sum of digits (38), and also a Moran number because the ratio is a prime number: 2136997 = 81205886 / (8 + 1 + 2 + 0 + 5 + 8 + 8 + 6).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1068461 + ... + 1068536.

It is an arithmetic number, because the mean of its divisors is an integer number (16027485).

Almost surely, 2^81205886 is an apocalyptic number.

81205886 is a deficient number, since it is larger than the sum of its proper divisors (47013994).

81205886 is a wasteful number, since it uses less digits than its factorization.

81205886 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2137018.

The product of its (nonzero) digits is 30720, while the sum is 38.

The square root of 81205886 is about 9011.4308519791. The cubic root of 81205886 is about 433.0411522810.

The spelling of 81205886 in words is "eighty-one million, two hundred five thousand, eight hundred eighty-six".