81111511 has 8 divisors (see below), whose sum is σ = 89712224. Its totient is φ = 72848160.

The previous prime is 81111451. The next prime is 81111529. The reversal of 81111511 is 11511118.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81111511 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81111011) 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, 83835 + ... + 84796.

It is an arithmetic number, because the mean of its divisors is an integer number (11214028).

Almost surely, 2^81111511 is an apocalyptic number.

81111511 is a deficient number, since it is larger than the sum of its proper divisors (8600713).

81111511 is a wasteful number, since it uses less digits than its factorization.

81111511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168681.

The product of its digits is 40, while the sum is 19.

The square root of 81111511 is about 9006.1929248712. The cubic root of 81111511 is about 432.8733315194.

Adding to 81111511 its reverse (11511118), we get a palindrome (92622629).

The spelling of 81111511 in words is "eighty-one million, one hundred eleven thousand, five hundred eleven".