81681047 has 8 divisors (see below), whose sum is σ = 94475136. Its totient is φ = 69168312.

The previous prime is 81681011. The next prime is 81681059. The reversal of 81681047 is 74018618.

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 81681047 - 2¹⁰ = 81680023 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81680998 and 81681016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81681077) 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, 69713 + ... + 70874.

It is an arithmetic number, because the mean of its divisors is an integer number (11809392).

Almost surely, 2^81681047 is an apocalyptic number.

81681047 is a deficient number, since it is larger than the sum of its proper divisors (12794089).

81681047 is a wasteful number, since it uses less digits than its factorization.

81681047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140677.

The product of its (nonzero) digits is 10752, while the sum is 35.

The square root of 81681047 is about 9037.7567460073. The cubic root of 81681047 is about 433.8841299119.

The spelling of 81681047 in words is "eighty-one million, six hundred eighty-one thousand, forty-seven".