81442579 has 4 divisors (see below), whose sum is σ = 81892720. Its totient is φ = 80992440.

The previous prime is 81442561. The next prime is 81442583. The reversal of 81442579 is 97524418.

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

It is a cyclic number.

It is not a de Polignac number, because 81442579 - 2⁵ = 81442547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81442279) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 224799 + ... + 225160.

It is an arithmetic number, because the mean of its divisors is an integer number (20473180).

Almost surely, 2^81442579 is an apocalyptic number.

81442579 is a deficient number, since it is larger than the sum of its proper divisors (450141).

81442579 is a wasteful number, since it uses less digits than its factorization.

81442579 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 450140.

The product of its digits is 80640, while the sum is 40.

The square root of 81442579 is about 9024.5542272181. The cubic root of 81442579 is about 433.4614764351.

The spelling of 81442579 in words is "eighty-one million, four hundred forty-two thousand, five hundred seventy-nine".