81637632 has 180 divisors, whose sum is σ = 253259776. Its totient is φ = 26127360.

The previous prime is 81637631. The next prime is 81637657. The reversal of 81637632 is 23673618.

It is a happy number.

81637632 is a `hidden beast` number, since 8 + 16 + 3 + 7 + 632 = 666.

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 (81637631) 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 19 ways as a sum of consecutive naturals, for example, 642753 + ... + 642879.

Almost surely, 2^81637632 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 81637632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (126629888).

81637632 is an abundant number, since it is smaller than the sum of its proper divisors (171622144).

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

81637632 is a wasteful number, since it uses less digits than its factorization.

81637632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186 (or 163 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 81637632 is about 9035.3545586214. The cubic root of 81637632 is about 433.8072437855.

The spelling of 81637632 in words is "eighty-one million, six hundred thirty-seven thousand, six hundred thirty-two".