81658725 has 12 divisors (see below), whose sum is σ = 135009216. Its totient is φ = 43551280.

The previous prime is 81658723. The next prime is 81658727. The reversal of 81658725 is 52785618.

It is an interprime number because it is at equal distance from previous prime (81658723) and next prime (81658727).

It is not a de Polignac number, because 81658725 - 2¹ = 81658723 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81658721) 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 11 ways as a sum of consecutive naturals, for example, 544317 + ... + 544466.

It is an arithmetic number, because the mean of its divisors is an integer number (11250768).

Almost surely, 2^81658725 is an apocalyptic number.

It is an amenable number.

81658725 is a deficient number, since it is larger than the sum of its proper divisors (53350491).

81658725 is a wasteful number, since it uses less digits than its factorization.

81658725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1088796 (or 1088791 counting only the distinct ones).

The product of its digits is 134400, while the sum is 42.

The square root of 81658725 is about 9036.5217312858. The cubic root of 81658725 is about 433.8446019990.

The spelling of 81658725 in words is "eighty-one million, six hundred fifty-eight thousand, seven hundred twenty-five".