81182578 has 4 divisors (see below), whose sum is σ = 121773870. Its totient is φ = 40591288.

The previous prime is 81182539. The next prime is 81182579. The reversal of 81182578 is 87528118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 66536649 + 14645929 = 8157^2 + 3827^2 .

It is a super-2 number, since 2×81182578² = 13181221941452168, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 81182578.

It is not an unprimeable number, because it can be changed into a prime (81182579) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20295643 + ... + 20295646.

Almost surely, 2^81182578 is an apocalyptic number.

81182578 is a deficient number, since it is larger than the sum of its proper divisors (40591292).

81182578 is a wasteful number, since it uses less digits than its factorization.

81182578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40591291.

The product of its digits is 35840, while the sum is 40.

The square root of 81182578 is about 9010.1375128241. The cubic root of 81182578 is about 432.9997173166. Note that the first 3 decimals are identical.

The spelling of 81182578 in words is "eighty-one million, one hundred eighty-two thousand, five hundred seventy-eight".