81236786 has 4 divisors (see below), whose sum is σ = 121855182. Its totient is φ = 40618392.

The previous prime is 81236783. The next prime is 81236791. The reversal of 81236786 is 68763218.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 68763218 = 2 ⋅34381609.

It can be written as a sum of positive squares in only one way, i.e., 78411025 + 2825761 = 8855^2 + 1681^2 .

It is not an unprimeable number, because it can be changed into a prime (81236783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20309195 + ... + 20309198.

Almost surely, 2^81236786 is an apocalyptic number.

81236786 is a deficient number, since it is larger than the sum of its proper divisors (40618396).

81236786 is a wasteful number, since it uses less digits than its factorization.

81236786 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40618395.

The product of its digits is 96768, while the sum is 41.

The square root of 81236786 is about 9013.1451780164. The cubic root of 81236786 is about 433.0960714312.

The spelling of 81236786 in words is "eighty-one million, two hundred thirty-six thousand, seven hundred eighty-six".