81663476 has 6 divisors (see below), whose sum is σ = 142911090. Its totient is φ = 40831736.

The previous prime is 81663443. The next prime is 81663479. The reversal of 81663476 is 67436618.

It can be written as a sum of positive squares in only one way, i.e., 68890000 + 12773476 = 8300^2 + 3574^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81663479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10207931 + ... + 10207938.

It is an arithmetic number, because the mean of its divisors is an integer number (23818515).

Almost surely, 2^81663476 is an apocalyptic number.

It is an amenable number.

81663476 is a deficient number, since it is larger than the sum of its proper divisors (61247614).

81663476 is a wasteful number, since it uses less digits than its factorization.

81663476 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20415873 (or 20415871 counting only the distinct ones).

The product of its digits is 145152, while the sum is 41.

The square root of 81663476 is about 9036.7846051569. The cubic root of 81663476 is about 433.8530156977.

The spelling of 81663476 in words is "eighty-one million, six hundred sixty-three thousand, four hundred seventy-six".