81657743 has 4 divisors (see below), whose sum is σ = 81735768. Its totient is φ = 81579720.

The previous prime is 81657733. The next prime is 81657787. The reversal of 81657743 is 34775618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34775618 = 2 ⋅17387809.

It is a cyclic number.

It is not a de Polignac number, because 81657743 - 2¹⁶ = 81592207 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 81657743.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81657733) 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, 37421 + ... + 39542.

It is an arithmetic number, because the mean of its divisors is an integer number (20433942).

Almost surely, 2^81657743 is an apocalyptic number.

81657743 is a deficient number, since it is larger than the sum of its proper divisors (78025).

81657743 is a wasteful number, since it uses less digits than its factorization.

81657743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78024.

The product of its digits is 141120, while the sum is 41.

The square root of 81657743 is about 9036.4673960569. The cubic root of 81657743 is about 433.8428629029.

The spelling of 81657743 in words is "eighty-one million, six hundred fifty-seven thousand, seven hundred forty-three".