81516672 has 128 divisors (see below), whose sum is σ = 243984000. Its totient is φ = 26790912.

The previous prime is 81516671. The next prime is 81516713. The reversal of 81516672 is 27661518.

81516672 is a `hidden beast` number, since 81 + 516 + 67 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (128).

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

It is not an unprimeable number, because it can be changed into a prime (81516671) 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, 355854 + ... + 356082.

It is an arithmetic number, because the mean of its divisors is an integer number (1906125).

Almost surely, 2^81516672 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 81516672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121992000).

81516672 is an abundant number, since it is smaller than the sum of its proper divisors (162467328).

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

81516672 is a wasteful number, since it uses less digits than its factorization.

81516672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355 (or 337 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 81516672 is about 9028.6583720949. The cubic root of 81516672 is about 433.5928848748.

The spelling of 81516672 in words is "eighty-one million, five hundred sixteen thousand, six hundred seventy-two".