81809446446 has 80 divisors (see below), whose sum is σ = 225616975584. Its totient is φ = 21576113856.

The previous prime is 81809446429. The next prime is 81809446447. The reversal of 81809446446 is 64464490818.

81809446446 is a `hidden beast` number, since 81 + 80 + 9 + 4 + 46 + 446 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 81809446392 and 81809446401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81809446447) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2759965 + ... + 2789448.

Almost surely, 2^81809446446 is an apocalyptic number.

81809446446 is an abundant number, since it is smaller than the sum of its proper divisors (143807529138).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81809446446 is a wasteful number, since it uses less digits than its factorization.

81809446446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5549447 (or 5549438 counting only the distinct ones).

The product of its (nonzero) digits is 5308416, while the sum is 54.

The spelling of 81809446446 in words is "eighty-one billion, eight hundred nine million, four hundred forty-six thousand, four hundred forty-six".