81538161 has 8 divisors (see below), whose sum is σ = 109041504. Its totient is φ = 54196800.

The previous prime is 81538141. The next prime is 81538181. The reversal of 81538161 is 16183518.

It is an interprime number because it is at equal distance from previous prime (81538141) and next prime (81538181).

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

It is not a de Polignac number, because 81538161 - 2¹¹ = 81536113 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81538141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39315 + ... + 41336.

It is an arithmetic number, because the mean of its divisors is an integer number (13630188).

Almost surely, 2^81538161 is an apocalyptic number.

It is an amenable number.

81538161 is a deficient number, since it is larger than the sum of its proper divisors (27503343).

81538161 is a wasteful number, since it uses less digits than its factorization.

81538161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80991.

The product of its digits is 5760, while the sum is 33.

The square root of 81538161 is about 9029.8483375968. The cubic root of 81538161 is about 433.6309820258.

The spelling of 81538161 in words is "eighty-one million, five hundred thirty-eight thousand, one hundred sixty-one".