81688418 has 16 divisors (see below), whose sum is σ = 144866880. Its totient is φ = 33801936.

The previous prime is 81688393. The next prime is 81688427. The reversal of 81688418 is 81488618.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 100196 + ... + 101007.

It is an arithmetic number, because the mean of its divisors is an integer number (9054180).

Almost surely, 2^81688418 is an apocalyptic number.

81688418 is a deficient number, since it is larger than the sum of its proper divisors (63178462).

81688418 is a wasteful number, since it uses less digits than its factorization.

81688418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 201241.

The product of its digits is 98304, while the sum is 44.

The square root of 81688418 is about 9038.1645260528. The cubic root of 81688418 is about 433.8971809351.

The spelling of 81688418 in words is "eighty-one million, six hundred eighty-eight thousand, four hundred eighteen".