81817632 has 162 divisors, whose sum is σ = 258238071. Its totient is φ = 24560640.

The previous prime is 81817627. The next prime is 81817639. The reversal of 81817632 is 23671818.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

81817632 is a `hidden beast` number, since 8 + 1 + 8 + 17 + 632 = 666.

It can be written as a sum of positive squares in 5 ways, for example, as 2322576 + 79495056 = 1524^2 + 8916^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=6396.

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 (81817639) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1995532 + ... + 1995572.

Almost surely, 2^81817632 is an apocalyptic number.

81817632 is a gapful number since it is divisible by the number (82) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81817632

81817632 is an abundant number, since it is smaller than the sum of its proper divisors (176420439).

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

81817632 is a wasteful number, since it uses less digits than its factorization.

81817632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124 (or 59 counting only the distinct ones).

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

The square root of 81817632 is about 9045.3099449383. The cubic root of 81817632 is about 434.1258386254.

The spelling of 81817632 in words is "eighty-one million, eight hundred seventeen thousand, six hundred thirty-two".