81667680 has 48 divisors (see below), whose sum is σ = 257254704. Its totient is φ = 21777920.

The previous prime is 81667669. The next prime is 81667721. The reversal of 81667680 is 8676618.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 84591 + ... + 85550.

It is an arithmetic number, because the mean of its divisors is an integer number (5359473).

Almost surely, 2^81667680 is an apocalyptic number.

81667680 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81667680 is an abundant number, since it is smaller than the sum of its proper divisors (175587024).

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

81667680 is a wasteful number, since it uses less digits than its factorization.

81667680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170159 (or 170151 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 42.

The square root of 81667680 is about 9037.0172070214. The cubic root of 81667680 is about 433.8604604244.

The spelling of 81667680 in words is "eighty-one million, six hundred sixty-seven thousand, six hundred eighty".