81533143 has 4 divisors (see below), whose sum is σ = 81919768. Its totient is φ = 81146520.

The previous prime is 81533129. The next prime is 81533197. The reversal of 81533143 is 34133518.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81533143 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 (81533743) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 192996 + ... + 193417.

It is an arithmetic number, because the mean of its divisors is an integer number (20479942).

Almost surely, 2^81533143 is an apocalyptic number.

81533143 is a deficient number, since it is larger than the sum of its proper divisors (386625).

81533143 is a wasteful number, since it uses less digits than its factorization.

81533143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386624.

The product of its digits is 4320, while the sum is 28.

The square root of 81533143 is about 9029.5704770493. The cubic root of 81533143 is about 433.6220863755.

The spelling of 81533143 in words is "eighty-one million, five hundred thirty-three thousand, one hundred forty-three".