81358366 has 4 divisors (see below), whose sum is σ = 122037552. Its totient is φ = 40679182.

The previous prime is 81358357. The next prime is 81358397. The reversal of 81358366 is 66385318.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20339590 + ... + 20339593.

It is an arithmetic number, because the mean of its divisors is an integer number (30509388).

Almost surely, 2^81358366 is an apocalyptic number.

81358366 is a deficient number, since it is larger than the sum of its proper divisors (40679186).

81358366 is a wasteful number, since it uses less digits than its factorization.

81358366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40679185.

The product of its digits is 103680, while the sum is 40.

The square root of 81358366 is about 9019.8872498496. The cubic root of 81358366 is about 433.3120227521.

The spelling of 81358366 in words is "eighty-one million, three hundred fifty-eight thousand, three hundred sixty-six".