81328947 has 8 divisors (see below), whose sum is σ = 123929856. Its totient is φ = 46473672.

The previous prime is 81328939. The next prime is 81328957. The reversal of 81328947 is 74982318.

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

It is not a de Polignac number, because 81328947 - 2³ = 81328939 is a prime.

It is a super-2 number, since 2×81328947² = 13228795240257618, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81328899 and 81328908.

It is not an unprimeable number, because it can be changed into a prime (81328927) 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, 1936383 + ... + 1936424.

It is an arithmetic number, because the mean of its divisors is an integer number (15491232).

Almost surely, 2^81328947 is an apocalyptic number.

81328947 is a deficient number, since it is larger than the sum of its proper divisors (42600909).

81328947 is a wasteful number, since it uses less digits than its factorization.

81328947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3872817.

The product of its digits is 96768, while the sum is 42.

The square root of 81328947 is about 9018.2563170493. The cubic root of 81328947 is about 433.2597882419.

The spelling of 81328947 in words is "eighty-one million, three hundred twenty-eight thousand, nine hundred forty-seven".