81658947 has 16 divisors (see below), whose sum is σ = 113833728. Its totient is φ = 51971040.

The previous prime is 81658909. The next prime is 81658949. The reversal of 81658947 is 74985618.

It is not a de Polignac number, because 81658947 - 2¹⁶ = 81593411 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 81658896 and 81658905.

It is not an unprimeable number, because it can be changed into a prime (81658949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52572 + ... + 54102.

It is an arithmetic number, because the mean of its divisors is an integer number (7114608).

Almost surely, 2^81658947 is an apocalyptic number.

81658947 is a deficient number, since it is larger than the sum of its proper divisors (32174781).

81658947 is a wasteful number, since it uses less digits than its factorization.

81658947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2330.

The product of its digits is 483840, while the sum is 48.

The square root of 81658947 is about 9036.5340147647. The cubic root of 81658947 is about 433.8449951532.

The spelling of 81658947 in words is "eighty-one million, six hundred fifty-eight thousand, nine hundred forty-seven".