81919360 has 64 divisors (see below), whose sum is σ = 202204800. Its totient is φ = 31703040.

The previous prime is 81919351. The next prime is 81919361. The reversal of 81919360 is 6391918.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81919361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17776 + ... + 21904.

It is an arithmetic number, because the mean of its divisors is an integer number (3159450).

Almost surely, 2^81919360 is an apocalyptic number.

81919360 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81919360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101102400).

81919360 is an abundant number, since it is smaller than the sum of its proper divisors (120285440).

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

81919360 is a wasteful number, since it uses less digits than its factorization.

81919360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4179 (or 4167 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 81919360 is about 9050.9314437797. The cubic root of 81919360 is about 434.3056876449.

The spelling of 81919360 in words is "eighty-one million, nine hundred nineteen thousand, three hundred sixty".