81686878 has 16 divisors (see below), whose sum is σ = 150806880. Its totient is φ = 32315616.

The previous prime is 81686863. The next prime is 81686879. The reversal of 81686878 is 87868618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81686879) 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, 224233 + ... + 224596.

It is an arithmetic number, because the mean of its divisors is an integer number (9425430).

Almost surely, 2^81686878 is an apocalyptic number.

81686878 is a deficient number, since it is larger than the sum of its proper divisors (69120002).

81686878 is a wasteful number, since it uses less digits than its factorization.

81686878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448851.

The product of its digits is 1032192, while the sum is 52.

The square root of 81686878 is about 9038.0793313624. The cubic root of 81686878 is about 433.8944542905.

The spelling of 81686878 in words is "eighty-one million, six hundred eighty-six thousand, eight hundred seventy-eight".