81668725 has 12 divisors (see below), whose sum is σ = 104536960. Its totient is φ = 63226800.

The previous prime is 81668693. The next prime is 81668729. The reversal of 81668725 is 52786618.

It is not a de Polignac number, because 81668725 - 2⁵ = 81668693 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81668729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 51915 + ... + 53464.

Almost surely, 2^81668725 is an apocalyptic number.

It is an amenable number.

81668725 is a deficient number, since it is larger than the sum of its proper divisors (22868235).

81668725 is a wasteful number, since it uses less digits than its factorization.

81668725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105420 (or 105415 counting only the distinct ones).

The product of its digits is 161280, while the sum is 43.

The square root of 81668725 is about 9037.0750245862. The cubic root of 81668725 is about 433.8623109412.

The spelling of 81668725 in words is "eighty-one million, six hundred sixty-eight thousand, seven hundred twenty-five".