81740647 has 4 divisors (see below), whose sum is σ = 84559320. Its totient is φ = 78921976.

The previous prime is 81740627. The next prime is 81740651. The reversal of 81740647 is 74604718.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81740647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81740627) 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, 1409293 + ... + 1409350.

It is an arithmetic number, because the mean of its divisors is an integer number (21139830).

Almost surely, 2^81740647 is an apocalyptic number.

81740647 is a deficient number, since it is larger than the sum of its proper divisors (2818673).

81740647 is a wasteful number, since it uses less digits than its factorization.

81740647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2818672.

The product of its (nonzero) digits is 37632, while the sum is 37.

The square root of 81740647 is about 9041.0534231360. The cubic root of 81740647 is about 433.9896346282.

The spelling of 81740647 in words is "eighty-one million, seven hundred forty thousand, six hundred forty-seven".