81684853 has 2 divisors, whose sum is σ = 81684854. Its totient is φ = 81684852.

The previous prime is 81684839. The next prime is 81684893. The reversal of 81684853 is 35848618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81396484 + 288369 = 9022^2 + 537^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81684853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81684893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40842426 + 40842427.

It is an arithmetic number, because the mean of its divisors is an integer number (40842427).

Almost surely, 2^81684853 is an apocalyptic number.

It is an amenable number.

81684853 is a deficient number, since it is larger than the sum of its proper divisors (1).

81684853 is an equidigital number, since it uses as much as digits as its factorization.

81684853 is an evil number, because the sum of its binary digits is even.

The product of its digits is 184320, while the sum is 43.

The square root of 81684853 is about 9037.9673046543. The cubic root of 81684853 is about 433.8908688777.

It can be divided in two parts, 8 and 1684853, that added together give a palindrome (1684861).

The spelling of 81684853 in words is "eighty-one million, six hundred eighty-four thousand, eight hundred fifty-three".