81691116 has 48 divisors (see below), whose sum is σ = 210837984. Its totient is φ = 24454656.

The previous prime is 81691111. The next prime is 81691117. The reversal of 81691116 is 61119618.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81691111) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1305 + ... + 12848.

It is an arithmetic number, because the mean of its divisors is an integer number (4392458).

Almost surely, 2^81691116 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81691116, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105418992).

81691116 is an abundant number, since it is smaller than the sum of its proper divisors (129146868).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81691116 is a wasteful number, since it uses less digits than its factorization.

81691116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14210 (or 14208 counting only the distinct ones).

The product of its digits is 2592, while the sum is 33.

The square root of 81691116 is about 9038.3137807890. The cubic root of 81691116 is about 433.9019577923.

The spelling of 81691116 in words is "eighty-one million, six hundred ninety-one thousand, one hundred sixteen".