81841825 has 24 divisors (see below), whose sum is σ = 115726968. Its totient is φ = 56878080.

The previous prime is 81841807. The next prime is 81841831. The reversal of 81841825 is 52814818.

It is a happy number.

It can be written as a sum of positive squares in 12 ways, for example, as 32855824 + 48986001 = 5732^2 + 6999^2 .

It is not a de Polignac number, because 81841825 - 2¹¹ = 81839777 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1882 + ... + 12931.

It is an arithmetic number, because the mean of its divisors is an integer number (4821957).

Almost surely, 2^81841825 is an apocalyptic number.

81841825 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81841825 is a deficient number, since it is larger than the sum of its proper divisors (33885143).

81841825 is a wasteful number, since it uses less digits than its factorization.

81841825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14853 (or 14848 counting only the distinct ones).

The product of its digits is 20480, while the sum is 37.

The square root of 81841825 is about 9046.6471689792. The cubic root of 81841825 is about 434.1686239074.

The spelling of 81841825 in words is "eighty-one million, eight hundred forty-one thousand, eight hundred twenty-five".