81099216 has 60 divisors (see below), whose sum is σ = 247603200. Its totient is φ = 24575040.

The previous prime is 81099211. The next prime is 81099233. The reversal of 81099216 is 61299018.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81099211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 24016 + ... + 27183.

It is an arithmetic number, because the mean of its divisors is an integer number (4126720).

Almost surely, 2^81099216 is an apocalyptic number.

It is an amenable number.

81099216 is an abundant number, since it is smaller than the sum of its proper divisors (166503984).

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

81099216 is a wasteful number, since it uses less digits than its factorization.

81099216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51224 (or 51215 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 81099216 is about 9005.5103131361. The cubic root of 81099216 is about 432.8514585592.

The spelling of 81099216 in words is "eighty-one million, ninety-nine thousand, two hundred sixteen".