81711789 has 8 divisors (see below), whose sum is σ = 109187232. Its totient is φ = 54355440.

The previous prime is 81711787. The next prime is 81711827. The reversal of 81711789 is 98711718.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81711789 - 2¹ = 81711787 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81711789.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81711781) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28159 + ... + 30924.

It is an arithmetic number, because the mean of its divisors is an integer number (13648404).

Almost surely, 2^81711789 is an apocalyptic number.

It is an amenable number.

81711789 is a deficient number, since it is larger than the sum of its proper divisors (27475443).

81711789 is a wasteful number, since it uses less digits than its factorization.

81711789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59547.

The product of its digits is 28224, while the sum is 42.

The square root of 81711789 is about 9039.4573399071. The cubic root of 81711789 is about 433.9385562176.

The spelling of 81711789 in words is "eighty-one million, seven hundred eleven thousand, seven hundred eighty-nine".