81996220 has 12 divisors (see below), whose sum is σ = 172192104. Its totient is φ = 32798480.

The previous prime is 81996203. The next prime is 81996221. The reversal of 81996220 is 2269918.

It is a self number, because there is not a number n which added to its sum of digits gives 81996220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81996221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2049886 + ... + 2049925.

It is an arithmetic number, because the mean of its divisors is an integer number (14349342).

Almost surely, 2^81996220 is an apocalyptic number.

It is an amenable number.

81996220 is an abundant number, since it is smaller than the sum of its proper divisors (90195884).

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

81996220 is a wasteful number, since it uses less digits than its factorization.

81996220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4099820 (or 4099818 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 81996220 is about 9055.1764201478. The cubic root of 81996220 is about 434.4414728076.

The spelling of 81996220 in words is "eighty-one million, nine hundred ninety-six thousand, two hundred twenty".