81825919 has 16 divisors (see below), whose sum is σ = 96841728. Its totient is φ = 67684032.

The previous prime is 81825917. The next prime is 81825929. The reversal of 81825919 is 91952818.

It is a cyclic number.

It is not a de Polignac number, because 81825919 - 2¹ = 81825917 is a prime.

It is a super-2 number, since 2×81825919² = 13390962040389122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81825917) 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 15 ways as a sum of consecutive naturals, for example, 22314 + ... + 25720.

It is an arithmetic number, because the mean of its divisors is an integer number (6052608).

Almost surely, 2^81825919 is an apocalyptic number.

81825919 is a deficient number, since it is larger than the sum of its proper divisors (15015809).

81825919 is a wasteful number, since it uses less digits than its factorization.

81825919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3534.

The product of its digits is 51840, while the sum is 43.

The square root of 81825919 is about 9045.7680160393. The cubic root of 81825919 is about 434.1404951213.

The spelling of 81825919 in words is "eighty-one million, eight hundred twenty-five thousand, nine hundred nineteen".