81840445 has 8 divisors (see below), whose sum is σ = 99452160. Its totient is φ = 64643280.

The previous prime is 81840439. The next prime is 81840449. The reversal of 81840445 is 54404818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81840445 - 2⁵ = 81840413 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81840445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81840449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103201 + ... + 103990.

It is an arithmetic number, because the mean of its divisors is an integer number (12431520).

Almost surely, 2^81840445 is an apocalyptic number.

It is an amenable number.

81840445 is a deficient number, since it is larger than the sum of its proper divisors (17611715).

81840445 is a wasteful number, since it uses less digits than its factorization.

81840445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207275.

The product of its (nonzero) digits is 20480, while the sum is 34.

The square root of 81840445 is about 9046.5708973069. The cubic root of 81840445 is about 434.1661836064.

The spelling of 81840445 in words is "eighty-one million, eight hundred forty thousand, four hundred forty-five".