81990024449 has 4 divisors (see below), whose sum is σ = 82579880880. Its totient is φ = 81400168020.

The previous prime is 81990024443. The next prime is 81990024451. The reversal of 81990024449 is 94442009918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81990024449 - 2¹⁶ = 81989958913 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81990024397 and 81990024406.

It is not an unprimeable number, because it can be changed into a prime (81990024443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 294928007 + ... + 294928284.

It is an arithmetic number, because the mean of its divisors is an integer number (20644970220).

Almost surely, 2^81990024449 is an apocalyptic number.

It is an amenable number.

81990024449 is a deficient number, since it is larger than the sum of its proper divisors (589856431).

81990024449 is a wasteful number, since it uses less digits than its factorization.

81990024449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 589856430.

The product of its (nonzero) digits is 746496, while the sum is 50.

The spelling of 81990024449 in words is "eighty-one billion, nine hundred ninety million, twenty-four thousand, four hundred forty-nine".