81138080 has 24 divisors (see below), whose sum is σ = 191689092. Its totient is φ = 32455168.

The previous prime is 81138073. The next prime is 81138091. The reversal of 81138080 is 8083118.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 73891216 + 7246864 = 8596^2 + 2692^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 253397 + ... + 253716.

Almost surely, 2^81138080 is an apocalyptic number.

81138080 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81138080 is an abundant number, since it is smaller than the sum of its proper divisors (110551012).

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

81138080 is a wasteful number, since it uses less digits than its factorization.

81138080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 507128 (or 507120 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 29.

The square root of 81138080 is about 9007.6678446754. The cubic root of 81138080 is about 432.9205905576.

The spelling of 81138080 in words is "eighty-one million, one hundred thirty-eight thousand, eighty".