81634320 has 60 divisors (see below), whose sum is σ = 274157676. Its totient is φ = 21768960.

The previous prime is 81634313. The next prime is 81634331. The reversal of 81634320 is 2343618.

It is a happy number.

81634320 is a `hidden beast` number, since 8 + 1 + 634 + 3 + 20 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 58247424 + 23386896 = 7632^2 + 4836^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 55971 + ... + 57410.

Almost surely, 2^81634320 is an apocalyptic number.

81634320 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81634320 is an abundant number, since it is smaller than the sum of its proper divisors (192523356).

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

81634320 is a wasteful number, since it uses less digits than its factorization.

81634320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113400 (or 113391 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 81634320 is about 9035.1712767385. The cubic root of 81634320 is about 433.8013772548.

Adding to 81634320 its reverse (2343618), we get a palindrome (83977938).

The spelling of 81634320 in words is "eighty-one million, six hundred thirty-four thousand, three hundred twenty".