81825637 has 4 divisors (see below), whose sum is σ = 83566656. Its totient is φ = 80084620.

The previous prime is 81825619. The next prime is 81825643. The reversal of 81825637 is 73652818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 73652818 = 2 ⋅36826409.

It is a cyclic number.

It is not a de Polignac number, because 81825637 - 2²³ = 73437029 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81825637.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81825677) 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 3 ways as a sum of consecutive naturals, for example, 870439 + ... + 870532.

It is an arithmetic number, because the mean of its divisors is an integer number (20891664).

Almost surely, 2^81825637 is an apocalyptic number.

It is an amenable number.

81825637 is a deficient number, since it is larger than the sum of its proper divisors (1741019).

81825637 is a wasteful number, since it uses less digits than its factorization.

81825637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1741018.

The product of its digits is 80640, while the sum is 40.

The square root of 81825637 is about 9045.7524286264. The cubic root of 81825637 is about 434.1399963887.

The spelling of 81825637 in words is "eighty-one million, eight hundred twenty-five thousand, six hundred thirty-seven".