81607680 has 528 divisors, whose sum is σ = 367870464. Its totient is φ = 16220160.

The previous prime is 81607639. The next prime is 81607693. The reversal of 81607680 is 8670618.

81607680 = 1191² + 1192² + ... + 1245².

It is a tau number, because it is divible by the number of its divisors (528).

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

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 3548149 + ... + 3548171.

Almost surely, 2^81607680 is an apocalyptic number.

81607680 is a gapful number since it is divisible by the number (80) 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 81607680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (183935232).

81607680 is an abundant number, since it is smaller than the sum of its proper divisors (286262784).

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

81607680 is a wasteful number, since it uses less digits than its factorization.

81607680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72 (or 51 counting only the distinct ones).

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

The square root of 81607680 is about 9033.6969176523. The cubic root of 81607680 is about 433.7541841707.

The spelling of 81607680 in words is "eighty-one million, six hundred seven thousand, six hundred eighty".