81557743 has 4 divisors (see below), whose sum is σ = 81610848. Its totient is φ = 81504640.

The previous prime is 81557719. The next prime is 81557753. The reversal of 81557743 is 34775518.

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

It is a cyclic number.

It is not a de Polignac number, because 81557743 - 2⁵ = 81557711 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81557696 and 81557705.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81557753) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24178 + ... + 27343.

It is an arithmetic number, because the mean of its divisors is an integer number (20402712).

Almost surely, 2^81557743 is an apocalyptic number.

81557743 is a deficient number, since it is larger than the sum of its proper divisors (53105).

81557743 is a wasteful number, since it uses less digits than its factorization.

81557743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53104.

The product of its digits is 117600, while the sum is 40.

The square root of 81557743 is about 9030.9325653556. The cubic root of 81557743 is about 433.6656924899.

The spelling of 81557743 in words is "eighty-one million, five hundred fifty-seven thousand, seven hundred forty-three".