81378216 has 128 divisors (see below), whose sum is σ = 241920000. Its totient is φ = 25272000.

The previous prime is 81378211. The next prime is 81378217. The reversal of 81378216 is 61287318.

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

It is not an unprimeable number, because it can be changed into a prime (81378211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 324091 + ... + 324341.

It is an arithmetic number, because the mean of its divisors is an integer number (1890000).

Almost surely, 2^81378216 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 81378216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120960000).

81378216 is an abundant number, since it is smaller than the sum of its proper divisors (160541784).

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

81378216 is a wasteful number, since it uses less digits than its factorization.

81378216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364 (or 354 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 81378216 is about 9020.9875290901. The cubic root of 81378216 is about 433.3472600389.

The spelling of 81378216 in words is "eighty-one million, three hundred seventy-eight thousand, two hundred sixteen".