81524642 has 4 divisors (see below), whose sum is σ = 122286966. Its totient is φ = 40762320.

The previous prime is 81524633. The next prime is 81524647. The reversal of 81524642 is 24642518.

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., 64144081 + 17380561 = 8009^2 + 4169^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81524599 and 81524608.

It is not an unprimeable number, because it can be changed into a prime (81524647) 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, 20381159 + ... + 20381162.

Almost surely, 2^81524642 is an apocalyptic number.

81524642 is a deficient number, since it is larger than the sum of its proper divisors (40762324).

81524642 is a wasteful number, since it uses less digits than its factorization.

81524642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40762323.

The product of its digits is 15360, while the sum is 32.

The square root of 81524642 is about 9029.0997336390. The cubic root of 81524642 is about 433.6070154103.

The spelling of 81524642 in words is "eighty-one million, five hundred twenty-four thousand, six hundred forty-two".