81711857 has 8 divisors (see below), whose sum is σ = 82944576. Its totient is φ = 80487792.

The previous prime is 81711827. The next prime is 81711859. The reversal of 81711857 is 75811718.

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

It is a cyclic number.

It is not a de Polignac number, because 81711857 - 2¹⁴ = 81695473 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81711857.

It is not an unprimeable number, because it can be changed into a prime (81711859) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18278 + ... + 22304.

It is an arithmetic number, because the mean of its divisors is an integer number (10368072).

Almost surely, 2^81711857 is an apocalyptic number.

It is an amenable number.

81711857 is a deficient number, since it is larger than the sum of its proper divisors (1232719).

81711857 is a wasteful number, since it uses less digits than its factorization.

81711857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4327.

The product of its digits is 15680, while the sum is 38.

The square root of 81711857 is about 9039.4611011940. The cubic root of 81711857 is about 433.9386765911.

It can be divided in two parts, 817118 and 57, that multiplied together give a triangular number (46575726 = T₉₆₅₁).

The spelling of 81711857 in words is "eighty-one million, seven hundred eleven thousand, eight hundred fifty-seven".