81663741 has 8 divisors (see below), whose sum is σ = 120983360. Its totient is φ = 54442476.

The previous prime is 81663737. The next prime is 81663749. The reversal of 81663741 is 14736618.

81663741 is a `hidden beast` number, since 8 + 16 + 637 + 4 + 1 = 666.

It is not a de Polignac number, because 81663741 - 2² = 81663737 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81663696 and 81663705.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81663749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1512265 + ... + 1512318.

It is an arithmetic number, because the mean of its divisors is an integer number (15122920).

Almost surely, 2^81663741 is an apocalyptic number.

It is an amenable number.

81663741 is a deficient number, since it is larger than the sum of its proper divisors (39319619).

81663741 is a wasteful number, since it uses less digits than its factorization.

81663741 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3024592 (or 3024586 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 81663741 is about 9036.7992674398. The cubic root of 81663741 is about 433.8534849851.

The spelling of 81663741 in words is "eighty-one million, six hundred sixty-three thousand, seven hundred forty-one".