81664608 has 24 divisors (see below), whose sum is σ = 214369848. Its totient is φ = 27221504.

The previous prime is 81664523. The next prime is 81664619. The reversal of 81664608 is 80646618.

It is a tau number, because it is divible by the number of its divisors (24).

It is a congruent number.

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, 425241 + ... + 425432.

It is an arithmetic number, because the mean of its divisors is an integer number (8932077).

Almost surely, 2^81664608 is an apocalyptic number.

It is an amenable number.

81664608 is an abundant number, since it is smaller than the sum of its proper divisors (132705240).

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

81664608 is a wasteful number, since it uses less digits than its factorization.

81664608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 850686 (or 850678 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 39.

The square root of 81664608 is about 9036.8472378369. The cubic root of 81664608 is about 433.8550203448.

The spelling of 81664608 in words is "eighty-one million, six hundred sixty-four thousand, six hundred eight".