81538847 has 4 divisors (see below), whose sum is σ = 87811080. Its totient is φ = 75266616.

The previous prime is 81538837. The next prime is 81538889. The reversal of 81538847 is 74883518.

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-81538847 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81538798 and 81538807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81538837) 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, 3136097 + ... + 3136122.

It is an arithmetic number, because the mean of its divisors is an integer number (21952770).

Almost surely, 2^81538847 is an apocalyptic number.

81538847 is a deficient number, since it is larger than the sum of its proper divisors (6272233).

81538847 is a wasteful number, since it uses less digits than its factorization.

81538847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6272232.

The product of its digits is 215040, while the sum is 44.

The square root of 81538847 is about 9029.8863226510. The cubic root of 81538847 is about 433.6321981027.

The spelling of 81538847 in words is "eighty-one million, five hundred thirty-eight thousand, eight hundred forty-seven".