81678672 has 80 divisors (see below), whose sum is σ = 239954880. Its totient is φ = 26587008.

The previous prime is 81678643. The next prime is 81678673. The reversal of 81678672 is 27687618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81678673) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16378 + ... + 20774.

It is an arithmetic number, because the mean of its divisors is an integer number (2999436).

Almost surely, 2^81678672 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 81678672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119977440).

81678672 is an abundant number, since it is smaller than the sum of its proper divisors (158276208).

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

81678672 is a wasteful number, since it uses less digits than its factorization.

81678672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4457 (or 4445 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The square root of 81678672 is about 9037.6253518278. The cubic root of 81678672 is about 433.8799245920.

The spelling of 81678672 in words is "eighty-one million, six hundred seventy-eight thousand, six hundred seventy-two".