81718533 has 48 divisors (see below), whose sum is σ = 133893760. Its totient is φ = 47682432.

The previous prime is 81718529. The next prime is 81718537. The reversal of 81718533 is 33581718.

It is an interprime number because it is at equal distance from previous prime (81718529) and next prime (81718537).

It is not a de Polignac number, because 81718533 - 2² = 81718529 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81718537) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 185928 + ... + 186366.

Almost surely, 2^81718533 is an apocalyptic number.

It is an amenable number.

81718533 is a deficient number, since it is larger than the sum of its proper divisors (52175227).

81718533 is a wasteful number, since it uses less digits than its factorization.

81718533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538 (or 535 counting only the distinct ones).

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

The square root of 81718533 is about 9039.8303634526. The cubic root of 81718533 is about 433.9504941160.

The spelling of 81718533 in words is "eighty-one million, seven hundred eighteen thousand, five hundred thirty-three".