81449136 has 60 divisors (see below), whose sum is σ = 234120432. Its totient is φ = 26414208.

The previous prime is 81449129. The next prime is 81449161. The reversal of 81449136 is 63194418.

81449136 is a `hidden beast` number, since 81 + 449 + 136 = 666.

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

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 81449136.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2316 + ... + 12971.

Almost surely, 2^81449136 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 81449136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117060216).

81449136 is an abundant number, since it is smaller than the sum of its proper divisors (152671296).

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

81449136 is a wasteful number, since it uses less digits than its factorization.

81449136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15338 (or 15329 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 81449136 is about 9024.9175065482. The cubic root of 81449136 is about 433.4731088869.

The spelling of 81449136 in words is "eighty-one million, four hundred forty-nine thousand, one hundred thirty-six".