81240578 has 4 divisors (see below), whose sum is σ = 121860870. Its totient is φ = 40620288.

The previous prime is 81240563. The next prime is 81240613. The reversal of 81240578 is 87504218.

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., 77387209 + 3853369 = 8797^2 + 1963^2 .

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 as a sum of consecutive naturals, namely, 20310143 + ... + 20310146.

Almost surely, 2^81240578 is an apocalyptic number.

81240578 is a deficient number, since it is larger than the sum of its proper divisors (40620292).

81240578 is a wasteful number, since it uses less digits than its factorization.

81240578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40620291.

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 81240578 is about 9013.3555349825. The cubic root of 81240578 is about 433.1028100646.

It can be divided in two parts, 81240 and 578, that added together give a palindrome (81818).

The spelling of 81240578 in words is "eighty-one million, two hundred forty thousand, five hundred seventy-eight".