81380388 has 12 divisors (see below), whose sum is σ = 189887600. Its totient is φ = 27126792.

The previous prime is 81380357. The next prime is 81380389. The reversal of 81380388 is 88308318.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (81380389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3390838 + ... + 3390861.

Almost surely, 2^81380388 is an apocalyptic number.

It is an amenable number.

81380388 is an abundant number, since it is smaller than the sum of its proper divisors (108507212).

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

81380388 is a wasteful number, since it uses less digits than its factorization.

81380388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6781706 (or 6781704 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 39.

The square root of 81380388 is about 9021.1079142198. The cubic root of 81380388 is about 433.3511153781.

The spelling of 81380388 in words is "eighty-one million, three hundred eighty thousand, three hundred eighty-eight".