81493788 has 12 divisors (see below), whose sum is σ = 190152200. Its totient is φ = 27164592.

The previous prime is 81493781. The next prime is 81493813. The reversal of 81493788 is 88739418.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81493781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3395563 + ... + 3395586.

Almost surely, 2^81493788 is an apocalyptic number.

It is an amenable number.

81493788 is an abundant number, since it is smaller than the sum of its proper divisors (108658412).

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

81493788 is a wasteful number, since it uses less digits than its factorization.

81493788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6791156 (or 6791154 counting only the distinct ones).

The product of its digits is 387072, while the sum is 48.

The square root of 81493788 is about 9027.3909852183. The cubic root of 81493788 is about 433.5523072115.

The spelling of 81493788 in words is "eighty-one million, four hundred ninety-three thousand, seven hundred eighty-eight".