81628425 has 96 divisors (see below), whose sum is σ = 159989760. Its totient is φ = 40737600.

The previous prime is 81628423. The next prime is 81628429. The reversal of 81628425 is 52482618.

81628425 is a `hidden beast` number, since 8 + 1 + 628 + 4 + 25 = 666.

It is not a de Polignac number, because 81628425 - 2¹ = 81628423 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81628425.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81628423) 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 95 ways as a sum of consecutive naturals, for example, 983434 + ... + 983516.

It is an arithmetic number, because the mean of its divisors is an integer number (1666560).

Almost surely, 2^81628425 is an apocalyptic number.

It is an amenable number.

81628425 is a deficient number, since it is larger than the sum of its proper divisors (78361335).

81628425 is a wasteful number, since it uses less digits than its factorization.

81628425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180 (or 169 counting only the distinct ones).

The product of its digits is 30720, while the sum is 36.

The square root of 81628425 is about 9034.8450457105. The cubic root of 81628425 is about 433.7909350753.

It can be divided in two parts, 816 and 28425, that added together give a square (29241 = 171²).

The spelling of 81628425 in words is "eighty-one million, six hundred twenty-eight thousand, four hundred twenty-five".