81536578 has 16 divisors (see below), whose sum is σ = 125773560. Its totient is φ = 39626496.

The previous prime is 81536513. The next prime is 81536599. The reversal of 81536578 is 87563518.

It can be written as a sum of positive squares in 4 ways, for example, as 78198649 + 3337929 = 8843^2 + 1827^2 .

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 8026 + ... + 15082.

Almost surely, 2^81536578 is an apocalyptic number.

81536578 is a deficient number, since it is larger than the sum of its proper divisors (44236982).

81536578 is a wasteful number, since it uses less digits than its factorization.

81536578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7221.

The product of its digits is 201600, while the sum is 43.

The square root of 81536578 is about 9029.7606834290. The cubic root of 81536578 is about 433.6281758049.

The spelling of 81536578 in words is "eighty-one million, five hundred thirty-six thousand, five hundred seventy-eight".