81658125 has 50 divisors (see below), whose sum is σ = 152524614. Its totient is φ = 43524000.

The previous prime is 81658121. The next prime is 81658141. The reversal of 81658125 is 52185618.

It can be written as a sum of positive squares in 5 ways, for example, as 27060804 + 54597321 = 5202^2 + 7389^2 .

It is not a de Polignac number, because 81658125 - 2² = 81658121 is a prime.

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

It is a self number, because there is not a number n which added to its sum of digits gives 81658125.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81658121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 49 ways as a sum of consecutive naturals, for example, 49819 + ... + 51431.

Almost surely, 2^81658125 is an apocalyptic number.

It is an amenable number.

81658125 is a deficient number, since it is larger than the sum of its proper divisors (70866489).

81658125 is an equidigital number, since it uses as much as digits as its factorization.

81658125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1645 (or 1621 counting only the distinct ones).

The product of its digits is 19200, while the sum is 36.

The square root of 81658125 is about 9036.4885326104. The cubic root of 81658125 is about 433.8435394165.

It can be divided in two parts, 8165 and 8125, that added together give a triangular number (16290 = T₁₈₀).

The spelling of 81658125 in words is "eighty-one million, six hundred fifty-eight thousand, one hundred twenty-five".