81117999 has 12 divisors (see below), whose sum is σ = 124063056. Its totient is φ = 50897472.

The previous prime is 81117989. The next prime is 81118003. The reversal of 81117999 is 99971118.

It is a de Polignac number, because none of the positive numbers 2^k-81117999 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81117919) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 264939 + ... + 265244.

It is an arithmetic number, because the mean of its divisors is an integer number (10338588).

Almost surely, 2^81117999 is an apocalyptic number.

81117999 is a deficient number, since it is larger than the sum of its proper divisors (42945057).

81117999 is a wasteful number, since it uses less digits than its factorization.

81117999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530206 (or 530203 counting only the distinct ones).

The product of its digits is 40824, while the sum is 45.

The square root of 81117999 is about 9006.5531142607. The cubic root of 81117999 is about 432.8848728623.

It can be divided in two parts, 8111 and 7999, that added together give a triangular number (16110 = T₁₇₉).

The spelling of 81117999 in words is "eighty-one million, one hundred seventeen thousand, nine hundred ninety-nine".