81885537 has 6 divisors (see below), whose sum is σ = 118279122. Its totient is φ = 54590352.

The previous prime is 81885533. The next prime is 81885577. The reversal of 81885537 is 73558818.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 42497361 + 39388176 = 6519^2 + 6276^2 .

It is not a de Polignac number, because 81885537 - 2² = 81885533 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81885492 and 81885501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81885533) 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 5 ways as a sum of consecutive naturals, for example, 4549188 + ... + 4549205.

It is an arithmetic number, because the mean of its divisors is an integer number (19713187).

Almost surely, 2^81885537 is an apocalyptic number.

It is an amenable number.

81885537 is a deficient number, since it is larger than the sum of its proper divisors (36393585).

81885537 is a wasteful number, since it uses less digits than its factorization.

81885537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9098399 (or 9098396 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The square root of 81885537 is about 9049.0627691491. The cubic root of 81885537 is about 434.2459071347.

The spelling of 81885537 in words is "eighty-one million, eight hundred eighty-five thousand, five hundred thirty-seven".