81308686 has 4 divisors (see below), whose sum is σ = 121963032. Its totient is φ = 40654342.

The previous prime is 81308683. The next prime is 81308707. The reversal of 81308686 is 68680318.

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

It is a super-2 number, since 2×81308686² = 13222204838093192, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81308681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20327170 + ... + 20327173.

It is an arithmetic number, because the mean of its divisors is an integer number (30490758).

Almost surely, 2^81308686 is an apocalyptic number.

81308686 is a deficient number, since it is larger than the sum of its proper divisors (40654346).

81308686 is a wasteful number, since it uses less digits than its factorization.

81308686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40654345.

The product of its (nonzero) digits is 55296, while the sum is 40.

The square root of 81308686 is about 9017.1329146242. The cubic root of 81308686 is about 433.2238067701.

The spelling of 81308686 in words is "eighty-one million, three hundred eight thousand, six hundred eighty-six".