81871557 has 8 divisors (see below), whose sum is σ = 109772640. Its totient is φ = 54275760.

The previous prime is 81871519. The next prime is 81871597. The reversal of 81871557 is 75517818.

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

It is not a de Polignac number, because 81871557 - 2¹¹ = 81869509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81871597) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75694 + ... + 76767.

It is an arithmetic number, because the mean of its divisors is an integer number (13721580).

Almost surely, 2^81871557 is an apocalyptic number.

It is an amenable number.

81871557 is a deficient number, since it is larger than the sum of its proper divisors (27901083).

81871557 is a wasteful number, since it uses less digits than its factorization.

81871557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152643.

The product of its digits is 78400, while the sum is 42.

The square root of 81871557 is about 9048.2902804895. The cubic root of 81871557 is about 434.2211933553.

It can be divided in two parts, 81871 and 557, that added together give a palindrome (82428).

The spelling of 81871557 in words is "eighty-one million, eight hundred seventy-one thousand, five hundred fifty-seven".