81771457 has 4 divisors (see below), whose sum is σ = 81869760. Its totient is φ = 81673156.

The previous prime is 81771451. The next prime is 81771491. The reversal of 81771457 is 75417718.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75417718 = 2 ⋅37708859.

It is a cyclic number.

It is not a de Polignac number, because 81771457 - 2³ = 81771449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81771451) 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, 47893 + ... + 49570.

It is an arithmetic number, because the mean of its divisors is an integer number (20467440).

Almost surely, 2^81771457 is an apocalyptic number.

It is an amenable number.

81771457 is a deficient number, since it is larger than the sum of its proper divisors (98303).

81771457 is an equidigital number, since it uses as much as digits as its factorization.

81771457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98302.

The product of its digits is 54880, while the sum is 40.

The square root of 81771457 is about 9042.7571569738. The cubic root of 81771457 is about 434.0441547946.

It can be divided in two parts, 81771 and 457, that added together give a palindrome (82228).

The spelling of 81771457 in words is "eighty-one million, seven hundred seventy-one thousand, four hundred fifty-seven".