81642444 has 24 divisors (see below), whose sum is σ = 205153200. Its totient is φ = 25120704.

The previous prime is 81642443. The next prime is 81642493. The reversal of 81642444 is 44424618.

It is not an unprimeable number, because it can be changed into a prime (81642443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 261519 + ... + 261830.

It is an arithmetic number, because the mean of its divisors is an integer number (8548050).

Almost surely, 2^81642444 is an apocalyptic number.

It is an amenable number.

81642444 is an abundant number, since it is smaller than the sum of its proper divisors (123510756).

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

81642444 is a wasteful number, since it uses less digits than its factorization.

81642444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 523369 (or 523367 counting only the distinct ones).

The product of its digits is 24576, while the sum is 33.

The square root of 81642444 is about 9035.6208419787. The cubic root of 81642444 is about 433.8157669768.

The spelling of 81642444 in words is "eighty-one million, six hundred forty-two thousand, four hundred forty-four".