81663253 has 6 divisors (see below), whose sum is σ = 94996086. Its totient is φ = 69997032.

The previous prime is 81663227. The next prime is 81663287. The reversal of 81663253 is 35236618.

It can be written as a sum of positive squares in only one way, i.e., 50381604 + 31281649 = 7098^2 + 5593^2 .

It is not a de Polignac number, because 81663253 - 2⁵ = 81663221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81663203) 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, 833250 + ... + 833347.

It is an arithmetic number, because the mean of its divisors is an integer number (15832681).

Almost surely, 2^81663253 is an apocalyptic number.

It is an amenable number.

81663253 is a deficient number, since it is larger than the sum of its proper divisors (13332833).

81663253 is a wasteful number, since it uses less digits than its factorization.

81663253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1666611 (or 1666604 counting only the distinct ones).

The product of its digits is 25920, while the sum is 34.

The square root of 81663253 is about 9036.7722666890. The cubic root of 81663253 is about 433.8526207871.

The spelling of 81663253 in words is "eighty-one million, six hundred sixty-three thousand, two hundred fifty-three".