81716436 has 18 divisors (see below), whose sum is σ = 206561082. Its totient is φ = 27238800.

The previous prime is 81716429. The next prime is 81716441. The reversal of 81716436 is 63461718.

81716436 is a `hidden beast` number, since 8 + 1 + 7 + 1 + 643 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 81108036 + 608400 = 9006^2 + 780^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 2269901 = 81716436 / (8 + 1 + 7 + 1 + 6 + 4 + 3 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 81716436.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1134915 + ... + 1134986.

Almost surely, 2^81716436 is an apocalyptic number.

It is an amenable number.

81716436 is an abundant number, since it is smaller than the sum of its proper divisors (124844646).

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

81716436 is a wasteful number, since it uses less digits than its factorization.

81716436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2269911 (or 2269906 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 81716436 is about 9039.7143760187. The cubic root of 81716436 is about 433.9467821797.

The spelling of 81716436 in words is "eighty-one million, seven hundred sixteen thousand, four hundred thirty-six".